class.ilDBPdoFieldDefinition.php

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<?php
 
abstract class ilDBPdoFieldDefinition
{
    const DEFAULT_DECIMAL_PLACES = 2;
    const DEFAULT_TEXT_LENGTH = 4000;
    const DEFINITION_COLUMN_NAME = "/^[a-z]+[_a-z0-9]*$/";
    const DEFINITION_TABLE_NAME = "/^[a-z]+[_a-z0-9]*$/";
    const INDEX_FORMAT = '%s_idx';
    const SEQUENCE_COLUMNS_NAME = 'sequence';
    const SEQUENCE_FORMAT = '%s_seq';
    const T_BLOB = 'blob';
    const T_CLOB = 'clob';
    const T_DATE = 'date';
    const T_DATETIME = 'datetime';
    const T_FLOAT = 'float';
    const T_INTEGER = 'integer';
    const T_TEXT = 'text';
    const T_TIME = 'time';
    const T_TIMESTAMP = 'timestamp';
    protected static $instance;
    public $allowed_attributes_old = array(
        self::T_TEXT      => array( 'length', 'notnull', 'default', 'fixed' ),
        self::T_INTEGER   => array( 'length', 'notnull', 'default', 'unsigned' ),
        self::T_FLOAT     => array( 'notnull', 'default' ),
        self::T_DATE      => array( 'notnull', 'default' ),
        self::T_TIME      => array( 'notnull', 'default' ),
        self::T_TIMESTAMP => array( 'notnull', 'default' ),
        self::T_CLOB      => array( 'notnull', 'default' ),
        self::T_BLOB      => array( 'notnull', 'default' ),
    );
    public $allowed_attributes = array(
        "text"      => array( "length", "notnull", "default", "fixed" ),
        "integer"   => array( "length", "notnull", "default", "unsigned" ),
        "float"     => array( "notnull", "default" ),
        "date"      => array( "notnull", "default" ),
        "time"      => array( "notnull", "default" ),
        "timestamp" => array( "notnull", "default" ),
        "clob"      => array( "length", "notnull", "default" ),
        "blob"      => array( "length", "notnull", "default" ),
    );
    protected $db_instance;
    protected $max_length = array(
        self::T_INTEGER => array( 1, 2, 3, 4, 8 ),
        self::T_TEXT    => 4000,
    );
    protected $available_types = array(
        self::T_TEXT,
        self::T_INTEGER,
        self::T_FLOAT,
        self::T_DATE,
        self::T_TIME,
        self::T_TIMESTAMP,
        self::T_CLOB,
        self::T_BLOB,
    );
    protected $reserved_mysql = array(
        "ACCESSIBLE",
        "ACCOUNT",
        "ACTION",
        "ADD",
        "AFTER",
        "AGAINST",
        "AGGREGATE",
        "ALGORITHM",
        "ALL",
        "ALTER",
        "ALWAYS",
        "ANALYSE",
        "ANALYZE",
        "AND",
        "ANY",
        "AS",
        "ASC",
        "ASCII",
        "ASENSITIVE",
        "AT",
        "AUTHORS",
        "AUTOEXTEND_SIZE",
        "AUTO_INCREMENT",
        "AVG",
        "AVG_ROW_LENGTH",
        "BACKUP",
        "BEFORE",
        "BEGIN",
        "BETWEEN",
        "BIGINT",
        "BINARY",
        "BINLOG",
        "BIT",
        "BLOB",
        "BLOCK",
        "BOOL",
        "BOOLEAN",
        "BOTH",
        "BTREE",
        "BY",
        "BYTE",
        "CACHE",
        "CALL",
        "CASCADE",
        "CASCADED",
        "CASE",
        "CATALOG_NAME",
        "CHAIN",
        "CHANGE",
        "CHANGED",
        "CHANNEL",
        "CHAR",
        "CHARACTER",
        "CHARSET",
        "CHECK",
        "CHECKSUM",
        "CIPHER",
        "CLASS_ORIGIN",
        "CLIENT",
        "CLOSE",
        "COALESCE",
        "CODE",
        "COLLATE",
        "COLLATION",
        "COLUMN",
        "COLUMNS",
        "COLUMN_FORMAT",
        "COLUMN_NAME",
        "COMMENT",
        "COMMIT",
        "COMMITTED",
        "COMPACT",
        "COMPLETION",
        "COMPRESSED",
        "COMPRESSION",
        "CONCURRENT",
        "CONDITION",
        "CONNECTION",
        "CONSISTENT",
        "CONSTRAINT",
        "CONSTRAINT_CATALOG",
        "CONSTRAINT_NAME",
        "CONSTRAINT_SCHEMA",
        "CONTAINS",
        "CONTEXT",
        "CONTINUE",
        "CONTRIBUTORS",
        "CONVERT",
        "CPU",
        "CREATE",
        "CROSS",
        "CUBE",
        "CURRENT",
        "CURRENT_DATE",
        "CURRENT_TIME",
        "CURRENT_TIMESTAMP",
        "CURRENT_USER",
        "CURSOR",
        "CURSOR_NAME",
        "DATA",
        "DATABASE",
        "DATABASES",
        "DATAFILE",
        "DATE",
        "DATETIME",
        "DAY",
        "DAY_HOUR",
        "DAY_MICROSECOND",
        "DAY_MINUTE",
        "DAY_SECOND",
        "DEALLOCATE",
        "DEC",
        "DECIMAL",
        "DECLARE",
        "DEFAULT",
        "DEFAULT_AUTH",
        "DEFINER",
        "DELAYED",
        "DELAY_KEY_WRITE",
        "DELETE",
        "DESC",
        "DESCRIBE",
        "DES_KEY_FILE",
        "DETERMINISTIC",
        "DIAGNOSTICS",
        "DIRECTORY",
        "DISABLE",
        "DISCARD",
        "DISK",
        "DISTINCT",
        "DISTINCTROW",
        "DIV",
        "DO",
        "DOUBLE",
        "DROP",
        "DUAL",
        "DUMPFILE",
        "DUPLICATE",
        "DYNAMIC",
        "EACH",
        "ELSE",
        "ELSEIF",
        "ENABLE",
        "ENCLOSED",
        "ENCRYPTION",
        "END",
        "ENDS",
        "ENGINE",
        "ENGINES",
        "ENUM",
        "ERROR",
        "ERRORS",
        "ESCAPE",
        "ESCAPED",
        "EVENT",
        "EVENTS",
        "EVERY",
        "EXCHANGE",
        "EXECUTE",
        "EXISTS",
        "EXIT",
        "EXPANSION",
        "EXPIRE",
        "EXPLAIN",
        "EXPORT",
        "EXTENDED",
        "EXTENT_SIZE",
        "FALSE",
        "FAST",
        "FAULTS",
        "FETCH",
        "FIELDS",
        "FILE",
        "FILE_BLOCK_SIZE",
        "FILTER",
        "FIRST",
        "FIXED",
        "FLOAT",
        "FLOAT4",
        "FLOAT8",
        "FLUSH",
        "FOLLOWS",
        "FOR",
        "FORCE",
        "FOREIGN",
        "FORMAT",
        "FOUND",
        "FROM",
        "FULL",
        "FULLTEXT",
        "FUNCTION",
        "GENERAL",
        "GENERATED",
        "GEOMETRY",
        "GEOMETRYCOLLECTION",
        "GET",
        "GET_FORMAT",
        "GLOBAL",
        "GRANT",
        "GRANTS",
        "GROUP",
        "GROUP_REPLICATION",
        "HANDLER",
        "HASH",
        "HAVING",
        "HELP",
        "HIGH_PRIORITY",
        "HOST",
        "HOSTS",
        "HOUR",
        "HOUR_MICROSECOND",
        "HOUR_MINUTE",
        "HOUR_SECOND",
        "IDENTIFIED",
        "IF",
        "IGNORE",
        "IGNORE_SERVER_IDS",
        "IMPORT",
        "IN",
        "INDEX",
        "INDEXES",
        "INFILE",
        "INITIAL_SIZE",
        "INNER",
        "INOUT",
        "INSENSITIVE",
        "INSERT",
        "INSERT_METHOD",
        "INSTALL",
        "INSTANCE",
        "INT",
        "INT1",
        "INT2",
        "INT3",
        "INT4",
        "INT8",
        "INTEGER",
        "INTERVAL",
        "INTO",
        "INVOKER",
        "IO",
        "IO_AFTER_GTIDS",
        "IO_BEFORE_GTIDS",
        "IO_THREAD",
        "IPC",
        "IS",
        "ISOLATION",
        "ISSUER",
        "ITERATE",
        "JOIN",
        "JSON",
        "KEY",
        "KEYS",
        "KEY_BLOCK_SIZE",
        "KILL",
        "LANGUAGE",
        "LAST",
        "LEADING",
        "LEAVE",
        "LEAVES",
        "LEFT",
        "LESS",
        "LEVEL",
        "LIKE",
        "LIMIT",
        "LINEAR",
        "LINES",
        "LINESTRING",
        "LIST",
        "LOAD",
        "LOCAL",
        "LOCALTIME",
        "LOCALTIMESTAMP",
        "LOCK",
        "LOCKS",
        "LOGFILE",
        "LOGS",
        "LONG",
        "LONGBLOB",
        "LONGTEXT",
        "LOOP",
        "LOW_PRIORITY",
        "MASTER",
        "MASTER_AUTO_POSITION",
        "MASTER_BIND",
        "MASTER_CONNECT_RETRY",
        "MASTER_DELAY",
        "MASTER_HEARTBEAT_PERIOD",
        "MASTER_HOST",
        "MASTER_LOG_FILE",
        "MASTER_LOG_POS",
        "MASTER_PASSWORD",
        "MASTER_PORT",
        "MASTER_RETRY_COUNT",
        "MASTER_SERVER_ID",
        "MASTER_SSL",
        "MASTER_SSL_CA",
        "MASTER_SSL_CAPATH",
        "MASTER_SSL_CERT",
        "MASTER_SSL_CIPHER",
        "MASTER_SSL_CRL",
        "MASTER_SSL_CRLPATH",
        "MASTER_SSL_KEY",
        "MASTER_SSL_VERIFY_SERVER_CERT",
        "MASTER_TLS_VERSION",
        "MASTER_USER",
        "MATCH",
        "MAXVALUE",
        "MAX_CONNECTIONS_PER_HOUR",
        "MAX_QUERIES_PER_HOUR",
        "MAX_ROWS",
        "MAX_SIZE",
        "MAX_STATEMENT_TIME",
        "MAX_UPDATES_PER_HOUR",
        "MAX_USER_CONNECTIONS",
        "MEDIUM",
        "MEDIUMBLOB",
        "MEDIUMINT",
        "MEDIUMTEXT",
        "MEMORY",
        "MERGE",
        "MESSAGE_TEXT",
        "MICROSECOND",
        "MIDDLEINT",
        "MIGRATE",
        "MINUTE",
        "MINUTE_MICROSECOND",
        "MINUTE_SECOND",
        "MIN_ROWS",
        "MOD",
        "MODE",
        "MODIFIES",
        "MODIFY",
        "MONTH",
        "MULTILINESTRING",
        "MULTIPOINT",
        "MULTIPOLYGON",
        "MUTEX",
        "MYSQL_ERRNO",
        "NAME",
        "NAMES",
        "NATIONAL",
        "NATURAL",
        "NCHAR",
        "NDB",
        "NDBCLUSTER",
        "NEVER",
        "NEW",
        "NEXT",
        "NO",
        "NODEGROUP",
        "NONBLOCKING",
        "NONE",
        "NOT",
        "NO_WAIT",
        "NO_WRITE_TO_BINLOG",
        "NULL",
        "NUMBER",
        "NUMERIC",
        "NVARCHAR",
        "OFFSET",
        "OLD_PASSWORD",
        "ON",
        "ONE",
        "ONE_SHOT",
        "ONLY",
        "OPEN",
        "OPTIMIZE",
        "OPTIMIZER_COSTS",
        "OPTION",
        "OPTIONALLY",
        "OPTIONS",
        "OR",
        "ORDER",
        "OUT",
        "OUTER",
        "OUTFILE",
        "OWNER",
        "PACK_KEYS",
        "PAGE",
        "PARSER",
        "PARSE_GCOL_EXPR",
        "PARTIAL",
        "PARTITION",
        "PARTITIONING",
        "PARTITIONS",
        "PASSWORD",
        "PHASE",
        "PLUGIN",
        "PLUGINS",
        "PLUGIN_DIR",
        "POINT",
        "POLYGON",
        "PORT",
        "PRECEDES",
        "PRECISION",
        "PREPARE",
        "PRESERVE",
        "PREV",
        "PRIMARY",
        "PRIVILEGES",
        "PROCEDURE",
        "PROCESSLIST",
        "PROFILE",
        "PROFILES",
        "PROXY",
        "PURGE",
        "QUARTER",
        "QUERY",
        "QUICK",
        "RANGE",
        "READ",
        "READS",
        "READ_ONLY",
        "READ_WRITE",
        "REAL",
        "REBUILD",
        "RECOVER",
        "REDOFILE",
        "REDO_BUFFER_SIZE",
        "REDUNDANT",
        "REFERENCES",
        "REGEXP",
        "RELAY",
        "RELAYLOG",
        "RELAY_LOG_FILE",
        "RELAY_LOG_POS",
        "RELAY_THREAD",
        "RELEASE",
        "RELOAD",
        "REMOVE",
        "RENAME",
        "REORGANIZE",
        "REPAIR",
        "REPEAT",
        "REPEATABLE",
        "REPLACE",
        "REPLICATE_DO_DB",
        "REPLICATE_DO_TABLE",
        "REPLICATE_IGNORE_DB",
        "REPLICATE_IGNORE_TABLE",
        "REPLICATE_REWRITE_DB",
        "REPLICATE_WILD_DO_TABLE",
        "REPLICATE_WILD_IGNORE_TABLE",
        "REPLICATION",
        "REQUIRE",
        "RESET",
        "RESIGNAL",
        "RESTORE",
        "RESTRICT",
        "RESUME",
        "RETURN",
        "RETURNED_SQLSTATE",
        "RETURNS",
        "REVERSE",
        "REVOKE",
        "RIGHT",
        "RLIKE",
        "ROLLBACK",
        "ROLLUP",
        "ROTATE",
        "ROUTINE",
        "ROW",
        "ROWS",
        "ROW_COUNT",
        "ROW_FORMAT",
        "RTREE",
        "SAVEPOINT",
        "SCHEDULE",
        "SCHEMA",
        "SCHEMAS",
        "SCHEMA_NAME",
        "SECOND",
        "SECOND_MICROSECOND",
        "SECURITY",
        "SELECT",
        "SENSITIVE",
        "SEPARATOR",
        "SERIAL",
        "SERIALIZABLE",
        "SERVER",
        "SESSION",
        "SET",
        "SHARE",
        "SHOW",
        "SHUTDOWN",
        "SIGNAL",
        "SIGNED",
        "SIMPLE",
        "SLAVE",
        "SLOW",
        "SMALLINT",
        "SNAPSHOT",
        "SOCKET",
        "SOME",
        "SONAME",
        "SOUNDS",
        "SOURCE",
        "SPATIAL",
        "SPECIFIC",
        "SQL",
        "SQLEXCEPTION",
        "SQLSTATE",
        "SQLWARNING",
        "SQL_AFTER_GTIDS",
        "SQL_AFTER_MTS_GAPS",
        "SQL_BEFORE_GTIDS",
        "SQL_BIG_RESULT",
        "SQL_BUFFER_RESULT",
        "SQL_CACHE",
        "SQL_CALC_FOUND_ROWS",
        "SQL_NO_CACHE",
        "SQL_SMALL_RESULT",
        "SQL_THREAD",
        "SQL_TSI_DAY",
        "SQL_TSI_HOUR",
        "SQL_TSI_MINUTE",
        "SQL_TSI_MONTH",
        "SQL_TSI_QUARTER",
        "SQL_TSI_SECOND",
        "SQL_TSI_WEEK",
        "SQL_TSI_YEAR",
        "SSL",
        "STACKED",
        "START",
        "STARTING",
        "STARTS",
        "STATS_AUTO_RECALC",
        "STATS_PERSISTENT",
        "STATS_SAMPLE_PAGES",
        "STATUS",
        "STOP",
        "STORAGE",
        "STORED",
        "STRAIGHT_JOIN",
        "STRING",
        "SUBCLASS_ORIGIN",
        "SUBJECT",
        "SUBPARTITION",
        "SUBPARTITIONS",
        "SUPER",
        "SUSPEND",
        "SWAPS",
        "SWITCHES",
        "TABLE",
        "TABLES",
        "TABLESPACE",
        "TABLE_CHECKSUM",
        "TABLE_NAME",
        "TEMPORARY",
        "TEMPTABLE",
        "TERMINATED",
        "TEXT",
        "THAN",
        "THEN",
        "TIME",
        "TIMESTAMP",
        "TIMESTAMPADD",
        "TIMESTAMPDIFF",
        "TINYBLOB",
        "TINYINT",
        "TINYTEXT",
        "TO",
        "TRAILING",
        "TRANSACTION",
        "TRIGGER",
        "TRIGGERS",
        "TRUE",
        "TRUNCATE",
        "TYPE",
        "TYPES",
        "UNCOMMITTED",
        "UNDEFINED",
        "UNDO",
        "UNDOFILE",
        "UNDO_BUFFER_SIZE",
        "UNICODE",
        "UNINSTALL",
        "UNION",
        "UNIQUE",
        "UNKNOWN",
        "UNLOCK",
        "UNSIGNED",
        "UNTIL",
        "UPDATE",
        "UPGRADE",
        "USAGE",
        "USE",
        "USER",
        "USER_RESOURCES",
        "USE_FRM",
        "USING",
        "UTC_DATE",
        "UTC_TIME",
        "UTC_TIMESTAMP",
        "VALIDATION",
        "VALUE",
        "VALUES",
        "VARBINARY",
        "VARCHAR",
        "VARCHARACTER",
        "VARIABLES",
        "VARYING",
        "VIEW",
        "VIRTUAL",
        "WAIT",
        "WARNINGS",
        "WEEK",
        "WEIGHT_STRING",
        "WHEN",
        "WHERE",
        "WHILE",
        "WITH",
        "WITHOUT",
        "WORK",
        "WRAPPER",
        "WRITE",
        "X509",
        "XA",
        "XID",
        "XML",
        "XOR",
        "YEAR",
        "YEAR_MONTH",
        "ZEROFILL",
    );
    protected $reserved_postgres = array(
        "ALL",
        "ANALYSE",
        "ANALYZE",
        "AND",
        "ANY",
        "ARRAY",
        "AS",
        "ASC",
        "ASYMMETRIC",
        "AUTHORIZATION",
        "BETWEEN",
        "BINARY",
        "BOTH",
        "CASE",
        "CAST",
        "CHECK",
        "COLLATE",
        "COLUMN",
        "CONSTRAINT",
        "CREATE",
        "CROSS",
        "CURRENT_DATE",
        "CURRENT_ROLE",
        "CURRENT_TIME",
        "CURRENT_TIMESTAMP",
        "CURRENT_USER",
        "DEFAULT",
        "DEFERRABLE",
        "DESC",
        "DISTINCT",
        "DO",
        "ELSE",
        "END",
        "EXCEPT",
        "FALSE",
        "FOR",
        "FOREIGN",
        "FREEZE",
        "FROM",
        "FULL",
        "GRANT",
        "GROUP",
        "HAVING",
        "ILIKE",
        "IN",
        "INITIALLY",
        "INNER",
        "INTERSECT",
        "INTO",
        "IS",
        "ISNULL",
        "JOIN",
        "LEADING",
        "LEFT",
        "LIKE",
        "LIMIT",
        "LOCALTIME",
        "LOCALTIMESTAMP",
        "NATURAL",
        "NEW",
        "NOT",
        "NOTNULL",
        "NULL",
        "OFF",
        "OFFSET",
        "OLD",
        "ON",
        "ONLY",
        "OR",
        "ORDER",
        "OUTER",
        "OVERLAPS",
        "PLACING",
        "PRIMARY",
        "REFERENCES",
        "RETURNING",
        "RIGHT",
        "SELECT",
        "SESSION_USER",
        "SIMILAR",
        "SOME",
        "SYMMETRIC",
        "TABLE",
        "THEN",
        "TO",
        "TRAILING",
        "TRUE",
        "UNION",
        "UNIQUE",
        "USER",
        "USING",
        "VERBOSE",
        "WHEN",
        "WHERE",
        "WITH",
    );
    protected $reserved_oracle = array(
        "ACCESS",
        "ADD",
        "ALL",
        "ALTER",
        "AND",
        "ANY",
        "AS",
        "ASC",
        "AUDIT",
        "BETWEEN",
        "BY",
        "CHAR",
        "CHECK",
        "CLUSTER",
        "COLUMN",
        "COMMENT",
        "COMPRESS",
        "CONNECT",
        "CREATE",
        "CURRENT",
        "DATE",
        "DECIMAL",
        "DEFAULT",
        "DELETE",
        "DESC",
        "DISTINCT",
        "DROP",
        "ELSE",
        "EXCLUSIVE",
        "EXISTS",
        "FILE",
        "FLOAT",
        "FOR",
        "FROM",
        "GRANT",
        "GROUP",
        "HAVING",
        "IDENTIFIED",
        "IMMEDIATE",
        "IN",
        "INCREMENT",
        "INDEX",
        "INITIAL",
        "INSERT",
        "INTEGER",
        "INTERSECT",
        "INTO",
        "IS",
        "LEVEL",
        "LIKE",
        "LOCK",
        "LONG",
        "MAXEXTENTS",
        "MINUS",
        "MLSLABEL",
        "MODE",
        "MODIFY",
        "NOAUDIT",
        "NOCOMPRESS",
        "NOT",
        "NOWAIT",
        "NULL",
        "NUMBER",
        "OF",
        "OFFLINE",
        "ON",
        "ONLINE",
        "OPTION",
        "OR",
        "ORDER",
        "PCTFREE",
        "PRIOR",
        "PRIVILEGES",
        "PUBLIC",
        "RAW",
        "RENAME",
        "RESOURCE",
        "REVOKE",
        "ROW",
        "ROWID",
        "ROWNUM",
        "ROWS",
        "SELECT",
        "SESSION",
        "SET",
        "SHARE",
        "SIZE",
        "SMALLINT",
        "START",
        "SUCCESSFUL",
        "SYNONYM",
        "SYSDATE",
        "TABLE",
        "THEN",
        "TO",
        "TRIGGER",
        "UID",
        "UNION",
        "UNIQUE",
        "UPDATE",
        "USER",
        "VALIDATE",
        "VALUES",
        "VARCHAR",
        "VARCHAR2",
        "VIEW",
        "WHENEVER",
        "WHERE",
        "WITH",
    );
    protected $query_utils;
 
 
    public function __construct(\ilDBInterface $ilDBInterface)
    {
        $this->db_instance = $ilDBInterface;
    }
 
 
    protected function getQueryUtils()
    {
        if (!$this->query_utils) {
            $this->query_utils = new ilMySQLQueryUtils($this->db_instance);
        }
 
        return $this->query_utils;
    }
 
 
    protected $valid_default_values = array(
        'text'      => '',
        'boolean'   => true,
        'integer'   => 0,
        'decimal'   => 0.0,
        'float'     => 0.0,
        'timestamp' => '1970-01-01 00:00:00',
        'time'      => '00:00:00',
        'date'      => '1970-01-01',
        'clob'      => '',
        'blob'      => '',
    );
 
 
    public function checkTableName($table_name)
    {
        if (!preg_match(self::DEFINITION_TABLE_NAME, $table_name)) {
            throw new ilDatabaseException('Table name must only contain _a-z0-9 and must start with a-z.');
        }
 
        if ($this->isReserved($table_name)) {
            throw new ilDatabaseException("Invalid table name '" . $table_name . "' (Reserved Word).");
        }
 
        if (strtolower(substr($table_name, 0, 4)) == "sys_") {
            throw new ilDatabaseException("Invalid table name '" . $table_name . "'. Name must not start with 'sys_'.");
        }
 
        if (strlen($table_name) > 22) {
            throw new ilDatabaseException("Invalid table name '" . $table_name . "'. Maximum table identifer length is 22 bytes.");
        }
 
        return true;
    }
 
 
    public function isReserved($table_name)
    {
        return false;
    }
 
 
    public function getAllReserved()
    {
        return array_merge($this->getReservedMysql(), $this->getReservedOracle(), $this->getReservedPostgres());
    }
 
 
    public function getReservedMysql()
    {
        return $this->reserved_mysql;
    }
 
 
    public function setReservedMysql($reserved_mysql)
    {
        $this->reserved_mysql = $reserved_mysql;
    }
 
 
    public function getReservedPostgres()
    {
        return $this->reserved_postgres;
    }
 
 
    public function setReservedPostgres($reserved_postgres)
    {
        $this->reserved_postgres = $reserved_postgres;
    }
 
 
    public function getReservedOracle()
    {
        return $this->reserved_oracle;
    }
 
 
    public function setReservedOracle($reserved_oracle)
    {
        $this->reserved_oracle = $reserved_oracle;
    }
 
 
    public function checkColumnName($column_name)
    {
        if (!preg_match("/^[a-z]+[_a-z0-9]*$/", $column_name)) {
            throw new ilDatabaseException("Invalid column name '" . $column_name
                                          . "'. Column name must only contain _a-z0-9 and must start with a-z.");
        }
 
        if ($this->isReserved($column_name)) {
            throw new ilDatabaseException("Invalid column name '" . $column_name . "' (Reserved Word).");
        }
 
        if (strtolower(substr($column_name, 0, 4)) == "sys_") {
            throw new ilDatabaseException("Invalid column name '" . $column_name . "'. Name must not start with 'sys_'.");
        }
 
        if (strlen($column_name) > 30) {
            throw new ilDatabaseException("Invalid column name '" . $column_name . "'. Maximum column identifer length is 30 bytes.");
        }
 
        return true;
    }
 
 
    public function checkIndexName($a_name)
    {
        if (!preg_match("/^[a-z]+[_a-z0-9]*$/", $a_name)) {
            throw new ilDatabaseException("Invalid column name '" . $a_name . "'. Column name must only contain _a-z0-9 and must start with a-z.");
        }
 
        if ($this->isReserved($a_name)) {
            throw new ilDatabaseException("Invalid column name '" . $a_name . "' (Reserved Word).");
        }
 
        if (strlen($a_name) > 3) {
            throw new ilDatabaseException("Invalid index name '" . $a_name . "'. Maximum index identifer length is 3 bytes.");
        }
 
        return true;
    }
 
 
    public function checkColumnDefinition($a_def)
    {
        // check valid type
        if (!in_array($a_def["type"], $this->getAvailableTypes())) {
            switch ($a_def["type"]) {
                case "boolean":
                    throw new ilDatabaseException("Invalid column type '" . $a_def["type"] . "'. Use integer(1) instead.");
                    break;
 
                case "decimal":
                    throw new ilDatabaseException("Invalid column type '" . $a_def["type"] . "'. Use float or integer instead.");
                    break;
 
                default:
                    throw new ilDatabaseException("Invalid column type '" . $a_def["type"] . "'. Allowed types are: "
                                                  . implode(', ', $this->getAvailableTypes()));
            }
        }
 
        // check used attributes
        $allowed_attributes = $this->getAllowedAttributes();
        foreach ($a_def as $k => $v) {
            if ($k != "type" && !in_array($k, $allowed_attributes[$a_def["type"]])) {
                throw new ilDatabaseException("Attribute '" . $k . "' is not allowed for column type '" . $a_def["type"] . "'.");
            }
        }
 
        // type specific checks
        $max_length = $this->getMaxLength();
        switch ($a_def["type"]) {
            case self::T_TEXT:
                if ($a_def["length"] < 1 || $a_def["length"] > $max_length[self::T_TEXT]) {
                    if (isset($a_def["length"])) {
                        throw new ilDatabaseException("Invalid length '" . $a_def["length"] . "' for type text." . " Length must be >=1 and <= "
                                                      . $max_length[self::T_TEXT] . ".");
                    }
                }
                break;
 
            case self::T_INTEGER:
                if (!in_array($a_def["length"], $max_length[self::T_INTEGER])) {
                    if (isset($a_def["length"])) {
                        throw new ilDatabaseException("Invalid length '" . $a_def["length"] . "' for type integer." . " Length must be "
                                                      . implode(', ', $max_length[self::T_INTEGER]) . " (bytes).");
                    }
                }
                if ($a_def["unsigned"]) {
                    throw new ilDatabaseException("Unsigned attribut must not be true for type integer.");
                }
                break;
        }
 
        return true;
    }
 
 
    public function isAllowedAttribute($attribute, $type)
    {
        return in_array($attribute, $this->allowed_attributes[$type]);
    }
 
 
    public function getAvailableTypes()
    {
        return $this->available_types;
    }
 
 
    public function setAvailableTypes($available_types)
    {
        $this->available_types = $available_types;
    }
 
 
    public function getAllowedAttributes()
    {
        return $this->allowed_attributes;
    }
 
 
    public function setAllowedAttributes($allowed_attributes)
    {
        $this->allowed_attributes = $allowed_attributes;
    }
 
 
    public function getMaxLength()
    {
        return $this->max_length;
    }
 
 
    public function setMaxLength($max_length)
    {
        $this->max_length = $max_length;
    }
 
 
    protected function getDBInstance()
    {
        return $this->db_instance;
    }
 
 
    public function getValidTypes()
    {
        $types = $this->valid_default_values;
        $db = $this->getDBInstance();
 
        if (!empty($db->options['datatype_map'])) {
            foreach ($db->options['datatype_map'] as $type => $mapped_type) {
                if (array_key_exists($mapped_type, $types)) {
                    $types[$type] = $types[$mapped_type];
                } elseif (!empty($db->options['datatype_map_callback'][$type])) {
                    $parameter = array( 'type' => $type, 'mapped_type' => $mapped_type );
                    $default = call_user_func_array($db->options['datatype_map_callback'][$type], array( &$db, __FUNCTION__, $parameter ));
                    $types[$type] = $default;
                }
            }
        }
 
        return $types;
    }
 
 
    protected function checkResultTypes($types)
    {
        $types = is_array($types) ? $types : array( $types );
        foreach ($types as $key => $type) {
            if (!isset($this->valid_default_values[$type])) {
                $db = $this->getDBInstance();
                if (empty($db->options['datatype_map'][$type])) {
                    throw new ilDatabaseException($type . ' for ' . $key . ' is not a supported column type');
                }
            }
        }
 
        return $types;
    }
 
 
    protected function baseConvertResult($value, $type, $rtrim = true)
    {
        switch ($type) {
            case 'text':
                if ($rtrim) {
                    $value = rtrim($value);
                }
 
                return $value;
            case 'integer':
                return intval($value);
            case 'boolean':
                return !empty($value);
            case 'decimal':
                return $value;
            case 'float':
                return doubleval($value);
            case 'date':
                return $value;
            case 'time':
                return $value;
            case 'timestamp':
                return $value;
            case 'clob':
            case 'blob':
                $this->lobs[] = array(
                    'buffer'    => null,
                    'position'  => 0,
                    'lob_index' => null,
                    'endOfLOB'  => false,
                    'resource'  => $value,
                    'value'     => null,
                    'loaded'    => false,
                );
                end($this->lobs);
                $lob_index = key($this->lobs);
                $this->lobs[$lob_index]['lob_index'] = $lob_index;
 
                return fopen('MDB2LOB://' . $lob_index . '@' . $this->db_index, 'r+');
        }
 
        throw new ilDatabaseException('attempt to convert result value to an unknown type :' . $type);
    }
 
 
    public function convertResult($value, $type, $rtrim = true)
    {
        if (is_null($value)) {
            return null;
        }
        $db = $this->getDBInstance();
 
        if (!empty($db->options['datatype_map'][$type])) {
            $type = $db->options['datatype_map'][$type];
            if (!empty($db->options['datatype_map_callback'][$type])) {
                $parameter = array( 'type' => $type, 'value' => $value, 'rtrim' => $rtrim );
 
                return call_user_func_array($db->options['datatype_map_callback'][$type], array( &$db, __FUNCTION__, $parameter ));
            }
        }
 
        return $this->baseConvertResult($value, $type, $rtrim);
    }
 
 
    public function convertResultRow($types, $row, $rtrim = true)
    {
        $types = $this->sortResultFieldTypes(array_keys($row), $types);
        foreach ($row as $key => $value) {
            if (empty($types[$key])) {
                continue;
            }
            $value = $this->convertResult($row[$key], $types[$key], $rtrim);
 
            $row[$key] = $value;
        }
 
        return $row;
    }
 
    // }}}
    // {{{ _sortResultFieldTypes()
 
    protected function sortResultFieldTypes($columns, $types)
    {
        $n_cols = count($columns);
        $n_types = count($types);
        if ($n_cols > $n_types) {
            for ($i = $n_cols - $n_types; $i >= 0; $i--) {
                $types[] = null;
            }
        }
        $sorted_types = array();
        foreach ($columns as $col) {
            $sorted_types[$col] = null;
        }
        foreach ($types as $name => $type) {
            if (array_key_exists($name, $sorted_types)) {
                $sorted_types[$name] = $type;
                unset($types[$name]);
            }
        }
        // if there are left types in the array, fill the null values of the
        // sorted array with them, in order.
        if (count($types)) {
            reset($types);
            foreach (array_keys($sorted_types) as $k) {
                if (is_null($sorted_types[$k])) {
                    $sorted_types[$k] = current($types);
                    next($types);
                }
            }
        }
 
        return $sorted_types;
    }
 
 
    public function getDeclaration($type, $name, $field)
    {
        $db = $this->getDBInstance();
 
        if (!empty($db->options['datatype_map'][$type])) {
            $type = $db->options['datatype_map'][$type];
            if (!empty($db->options['datatype_map_callback'][$type])) {
                $parameter = array( 'type' => $type, 'name' => $name, 'field' => $field );
 
                return call_user_func_array($db->options['datatype_map_callback'][$type], array( &$db, __FUNCTION__, $parameter ));
            }
            $field['type'] = $type;
        }
 
        if (!method_exists($this, "get{$type}Declaration")) {
            throw new ilDatabaseException('type not defined: ' . $type);
        }
 
        return $this->{"get{$type}Declaration"}($name, $field);
    }
 
 
    public function getTypeDeclaration($field)
    {
        $db = $this->getDBInstance();
 
        switch ($field['type']) {
            case 'text':
                $length = !empty($field['length']) ? $field['length'] : $db->options['default_text_field_length'];
                $fixed = !empty($field['fixed']) ? $field['fixed'] : false;
 
                return $fixed ? ($length ? 'CHAR(' . $length . ')' : 'CHAR(' . $db->options['default_text_field_length']
                                                                     . ')') : ($length ? 'VARCHAR(' . $length . ')' : 'TEXT');
            case 'clob':
                return 'TEXT';
            case 'blob':
                return 'TEXT';
            case 'integer':
                return 'INT';
            case 'boolean':
                return 'INT';
            case 'date':
                return 'CHAR (' . strlen('YYYY-MM-DD') . ')';
            case 'time':
                return 'CHAR (' . strlen('HH:MM:SS') . ')';
            case 'timestamp':
                return 'CHAR (' . strlen('YYYY-MM-DD HH:MM:SS') . ')';
            case 'float':
                return 'TEXT';
            case 'decimal':
                return 'TEXT';
        }
 
        return '';
    }
 
 
    protected function getInternalDeclaration($name, $field)
    {
        $db = $this->getDBInstance();
 
        $name = $db->quoteIdentifier($name, true);
        $declaration_options = $db->getFieldDefinition()->getDeclarationOptions($field);
 
        return $name . ' ' . $this->getTypeDeclaration($field) . $declaration_options;
    }
 
 
    protected function getDeclarationOptions($field)
    {
        $charset = empty($field['charset']) ? '' : ' ' . $this->getCharsetFieldDeclaration($field['charset']);
 
        $default = '';
        if (array_key_exists('default', $field)) {
            if ($field['default'] === '') {
                $db = $this->getDBInstance();
 
                if (empty($field['notnull'])) {
                    $field['default'] = null;
                } else {
                    $valid_default_values = $this->getValidTypes();
                    $field['default'] = $valid_default_values[$field['type']];
                }
                if ($field['default'] === ''
                    && ($db->options['portability'] & 32)
                ) {
                    $field['default'] = ' ';
                }
            }
            $default = ' DEFAULT ' . $this->quote($field['default'], $field['type']);
        } elseif (empty($field['notnull'])) {
            $default = ' DEFAULT NULL';
        }
 
        $notnull = empty($field['notnull']) ? '' : ' NOT NULL';
        // alex patch 28 Nov 2011 start
        if ($field['notnull'] === false) {
            $notnull = " NULL";
        }
        // alex patch 28 Nov 2011 end
 
        $collation = empty($field['collation']) ? '' : ' ' . $this->getCollationFieldDeclaration($field['collation']);
 
        return $charset . $default . $notnull . $collation;
    }
 
 
    protected function getCharsetFieldDeclaration($charset)
    {
        return '';
    }
 
 
    protected function getCollationFieldDeclaration($collation)
    {
        return '';
    }
 
 
    protected function getIntegerDeclaration($name, $field)
    {
        if (!empty($field['unsigned'])) {
            $db = $this->getDBInstance();
 
            $db->warnings[] = "unsigned integer field \"$name\" is being declared as signed integer";
        }
 
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getTextDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getCLOBDeclaration($name, $field)
    {
        $db = $this->getDBInstance();
 
        $notnull = empty($field['notnull']) ? '' : ' NOT NULL';
        $name = $db->quoteIdentifier($name, true);
 
        return $name . ' ' . $this->getTypeDeclaration($field) . $notnull;
    }
 
 
    protected function getBLOBDeclaration($name, $field)
    {
        $db = $this->getDBInstance();
 
        $notnull = empty($field['notnull']) ? '' : ' NOT NULL';
        $name = $db->quoteIdentifier($name, true);
 
        return $name . ' ' . $this->getTypeDeclaration($field) . $notnull;
    }
 
 
    protected function getBooleanDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getDateDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getTimestampDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getTimeDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getFloatDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    protected function getDecimalDeclaration($name, $field)
    {
        return $this->getInternalDeclaration($name, $field);
    }
 
 
    public function compareDefinition($current, $previous)
    {
        $type = !empty($current['type']) ? $current['type'] : null;
 
        if (!method_exists($this, "compare{$type}Definition")) {
            $db = $this->getDBInstance();
 
            if (!empty($db->options['datatype_map_callback'][$type])) {
                $parameter = array( 'current' => $current, 'previous' => $previous );
                $change = call_user_func_array($db->options['datatype_map_callback'][$type], array( &$db, __FUNCTION__, $parameter ));
 
                return $change;
            }
 
            throw new ilDatabaseException('type "' . $current['type'] . '" is not yet supported');
        }
 
        if (empty($previous['type']) || $previous['type'] != $type) {
            return $current;
        }
 
        $change = $this->{"compare{$type}Definition"}($current, $previous);
 
        if ($previous['type'] != $type) {
            $change['type'] = true;
        }
 
        $previous_notnull = !empty($previous['notnull']) ? $previous['notnull'] : false;
        $notnull = !empty($current['notnull']) ? $current['notnull'] : false;
        if ($previous_notnull != $notnull) {
            $change['notnull'] = true;
        }
 
        $previous_default = array_key_exists('default', $previous) ? $previous['default'] : ($previous_notnull ? '' : null);
        $default = array_key_exists('default', $current) ? $current['default'] : ($notnull ? '' : null);
        if ($previous_default !== $default) {
            $change['default'] = true;
        }
 
        return $change;
    }
 
 
    protected function compareIntegerDefinition($current, $previous)
    {
        $change = array();
        $previous_unsigned = !empty($previous['unsigned']) ? $previous['unsigned'] : false;
        $unsigned = !empty($current['unsigned']) ? $current['unsigned'] : false;
        if ($previous_unsigned != $unsigned) {
            $change['unsigned'] = true;
        }
        $previous_autoincrement = !empty($previous['autoincrement']) ? $previous['autoincrement'] : false;
        $autoincrement = !empty($current['autoincrement']) ? $current['autoincrement'] : false;
        if ($previous_autoincrement != $autoincrement) {
            $change['autoincrement'] = true;
        }
 
        return $change;
    }
 
 
    protected function compareTextDefinition($current, $previous)
    {
        $change = array();
        $previous_length = !empty($previous['length']) ? $previous['length'] : 0;
        $length = !empty($current['length']) ? $current['length'] : 0;
        if ($previous_length != $length) {
            $change['length'] = true;
        }
        $previous_fixed = !empty($previous['fixed']) ? $previous['fixed'] : 0;
        $fixed = !empty($current['fixed']) ? $current['fixed'] : 0;
        if ($previous_fixed != $fixed) {
            $change['fixed'] = true;
        }
 
        return $change;
    }
 
 
    protected function compareCLOBDefinition($current, $previous)
    {
        return $this->compareTextDefinition($current, $previous);
    }
 
 
    protected function compareBLOBDefinition($current, $previous)
    {
        return $this->compareTextDefinition($current, $previous);
    }
 
 
    protected function compareDateDefinition($current, $previous)
    {
        return array();
    }
 
 
    protected function compareTimeDefinition($current, $previous)
    {
        return array();
    }
 
 
    protected function compareTimestampDefinition($current, $previous)
    {
        return array();
    }
 
 
    protected function compareBooleanDefinition($current, $previous)
    {
        return array();
    }
 
 
    protected function compareFloatDefinition($current, $previous)
    {
        return array();
    }
 
 
    protected function compareDecimalDefinition($current, $previous)
    {
        return array();
    }
 
 
    public function quote($value, $type = null, $quote = true, $escape_wildcards = false)
    {
        $db = $this->getDBInstance();
 
        return $db->quote($value, $type);
 
        if (is_null($value)
            || ($value === '' && $db->options['portability'] & MDB2_PORTABILITY_EMPTY_TO_NULL)
        ) {
            if (!$quote) {
                return null;
            }
 
            return 'NULL';
        }
 
        if (is_null($type)) {
            switch (gettype($value)) {
                case 'integer':
                    $type = 'integer';
                    break;
                case 'double':
                    // todo: default to decimal as float is quite unusual
                    // $type = 'float';
                    $type = 'decimal';
                    break;
                case 'boolean':
                    $type = 'boolean';
                    break;
                case 'array':
                    $value = serialize($value);
                    // no break
                case 'object':
                    $type = 'text';
                    break;
                default:
                    if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}$/', $value)) {
                        $type = 'timestamp';
                    } elseif (preg_match('/^\d{2}:\d{2}$/', $value)) {
                        $type = 'time';
                    } elseif (preg_match('/^\d{4}-\d{2}-\d{2}$/', $value)) {
                        $type = 'date';
                    } else {
                        $type = 'text';
                    }
                    break;
            }
        } elseif (!empty($db->options['datatype_map'][$type])) {
            $type = $db->options['datatype_map'][$type];
            if (!empty($db->options['datatype_map_callback'][$type])) {
                $parameter = array( 'type' => $type, 'value' => $value, 'quote' => $quote, 'escape_wildcards' => $escape_wildcards );
 
                return call_user_func_array($db->options['datatype_map_callback'][$type], array( &$db, __FUNCTION__, $parameter ));
            }
        }
 
        if (!method_exists($this, "quote{$type}")) {
            throw new ilDatabaseException('type not defined: ' . $type);
        }
        $value = $this->{"quote{$type}"}($value, $quote, $escape_wildcards);
        if ($quote && $escape_wildcards && $db->string_quoting['escape_pattern']
            && $db->string_quoting['escape'] !== $db->string_quoting['escape_pattern']
        ) {
            $value .= $this->patternEscapeString();
        }
 
        return $value;
    }
 
 
    protected function quoteInteger($value, $quote, $escape_wildcards)
    {
        return (int) $value;
    }
 
 
    protected function quoteText($value, $quote, $escape_wildcards)
    {
        if (!$quote) {
            return $value;
        }
 
        $db = $this->getDBInstance();
 
        $value = $db->escape($value, $escape_wildcards);
 
        return "'" . $value . "'";
    }
 
 
    protected function readFile($value)
    {
        $close = false;
        if (preg_match('/^(\w+:\/\/)(.*)$/', $value, $match)) {
            $close = true;
            if ($match[1] == 'file://') {
                $value = $match[2];
            }
            // do not try to open urls
            #$value = @fopen($value, 'r');
        }
 
        if (is_resource($value)) {
            $db = $this->getDBInstance();
 
            $fp = $value;
            $value = '';
            while (!@feof($fp)) {
                $value .= @fread($fp, $db->options['lob_buffer_length']);
            }
            if ($close) {
                @fclose($fp);
            }
        }
 
        return $value;
    }
 
 
    protected function quoteLOB($value, $quote, $escape_wildcards)
    {
        $value = $this->readFile($value);
 
        return $this->quoteText($value, $quote, $escape_wildcards);
    }
 
 
    protected function quoteCLOB($value, $quote, $escape_wildcards)
    {
        return $this->quoteLOB($value, $quote, $escape_wildcards);
    }
 
 
    protected function quoteBLOB($value, $quote, $escape_wildcards)
    {
        return $this->quoteLOB($value, $quote, $escape_wildcards);
    }
 
 
    protected function quoteBoolean($value, $quote, $escape_wildcards)
    {
        return ($value ? 1 : 0);
    }
 
 
    protected function quoteDate($value, $quote, $escape_wildcards)
    {
        if ($value === 'CURRENT_DATE') {
            $db = $this->getDBInstance();
 
            return 'CURRENT_DATE';
        }
 
        return $this->quoteText($value, $quote, $escape_wildcards);
    }
 
 
    protected function quoteTimestamp($value, $quote, $escape_wildcards)
    {
        if ($value === 'CURRENT_TIMESTAMP') {
            $db = $this->getDBInstance();
 
            if (isset($db->function) && is_a($db->function, 'MDB2_Driver_Function_Common')) {
                return $db->function->now('timestamp');
            }
 
            return 'CURRENT_TIMESTAMP';
        }
 
        return $this->quoteText($value, $quote, $escape_wildcards);
    }
 
 
    protected function quoteTime($value, $quote, $escape_wildcards)
    {
        if ($value === 'CURRENT_TIME') {
            $db = $this->getDBInstance();
 
            if (isset($db->function) && is_a($db->function, 'MDB2_Driver_Function_Common')) {
                return $db->function->now('time');
            }
 
            return 'CURRENT_TIME';
        }
 
        return $this->quoteText($value, $quote, $escape_wildcards);
    }
 
 
    protected function quoteFloat($value, $quote, $escape_wildcards)
    {
        if (preg_match('/^(.*)e([-+])(\d+)$/i', $value, $matches)) {
            $decimal = $this->quoteDecimal($matches[1], $quote, $escape_wildcards);
            $sign = $matches[2];
            $exponent = str_pad($matches[3], 2, '0', STR_PAD_LEFT);
            $value = $decimal . 'E' . $sign . $exponent;
        } else {
            $value = $this->quoteDecimal($value, $quote, $escape_wildcards);
        }
 
        return $value;
    }
 
 
    protected function quoteDecimal($value, $quote, $escape_wildcards)
    {
        $value = (string) $value;
        $value = preg_replace('/[^\d\.,\-+eE]/', '', $value);
        if (preg_match('/[^.0-9]/', $value)) {
            if (strpos($value, ',')) {
                // 1000,00
                if (!strpos($value, '.')) {
                    // convert the last "," to a "."
                    $value = strrev(str_replace(',', '.', strrev($value)));
                // 1.000,00
                } elseif (strpos($value, '.') && strpos($value, '.') < strpos($value, ',')) {
                    $value = str_replace('.', '', $value);
                    // convert the last "," to a "."
                    $value = strrev(str_replace(',', '.', strrev($value)));
                // 1,000.00
                } else {
                    $value = str_replace(',', '', $value);
                }
            }
        }
 
        return $value;
    }
 
 
    public function writeLOBToFile($lob, $file)
    {
        $db = $this->getDBInstance();
 
        if (preg_match('/^(\w+:\/\/)(.*)$/', $file, $match)) {
            if ($match[1] == 'file://') {
                $file = $match[2];
            }
        }
 
        $fp = @fopen($file, 'wb');
        while (!@feof($lob)) {
            $result = @fread($lob, $db->options['lob_buffer_length']);
            $read = strlen($result);
            if (@fwrite($fp, $result, $read) != $read) {
                @fclose($fp);
 
                throw new ilDatabaseException('could not write to the output file');
            }
        }
        @fclose($fp);
 
        return MDB2_OK;
    }
 
 
    protected function retrieveLOB(&$lob)
    {
        if (is_null($lob['value'])) {
            $lob['value'] = $lob['resource'];
        }
        $lob['loaded'] = true;
 
        return MDB2_OK;
    }
 
 
    protected function readLOB($lob, $length)
    {
        return substr($lob['value'], $lob['position'], $length);
    }
 
 
    protected function endOfLOB($lob)
    {
        return $lob['endOfLOB'];
    }
 
 
    public function destroyLOB($lob)
    {
        $lob_data = stream_get_meta_data($lob);
        $lob_index = $lob_data['wrapper_data']->lob_index;
        fclose($lob);
        if (isset($this->lobs[$lob_index])) {
            $this->destroyLOBInternal($this->lobs[$lob_index]);
            unset($this->lobs[$lob_index]);
        }
 
        return true;
    }
 
 
    protected function destroyLOBInternal(&$lob)
    {
        return true;
    }
 
 
    public function implodeArray($array, $type = false)
    {
        if (!is_array($array) || empty($array)) {
            return 'NULL';
        }
        if ($type) {
            foreach ($array as $value) {
                $return[] = $this->quote($value, $type);
            }
        } else {
            $return = $array;
        }
 
        return implode(', ', $return);
    }
 
 
    public function matchPattern($pattern, $operator = null, $field = null)
    {
        $db = $this->getDBInstance();
 
        $match = '';
        if (!is_null($operator)) {
            $operator = strtoupper($operator);
            switch ($operator) {
                // case insensitive
                case 'ILIKE':
                    if (is_null($field)) {
                        throw new ilDatabaseException('case insensitive LIKE matching requires passing the field name');
                    }
                    $db->loadModule('Function', null, true);
                    $match = $db->function->lower($field) . ' LIKE ';
                    break;
                // case sensitive
                case 'LIKE':
                    $match = is_null($field) ? 'LIKE ' : $field . ' LIKE ';
                    break;
                default:
                    throw new ilDatabaseException('not a supported operator type:' . $operator);
            }
        }
        $match .= "'";
        foreach ($pattern as $key => $value) {
            if ($key % 2) {
                $match .= $value;
            } else {
                if ($operator === 'ILIKE') {
                    $value = strtolower($value);
                }
                $escaped = $db->escape($value);
                $match .= $db->escapePattern($escaped);
            }
        }
        $match .= "'";
        $match .= $this->patternEscapeString();
 
        return $match;
    }
 
 
    public function patternEscapeString()
    {
        return '';
    }
 
 
    public function mapNativeDatatype($field)
    {
        $db = $this->getDBInstance();
        $db_type = strtok($field['type'], '(), ');
        if (!empty($db->options['nativetype_map_callback'][$db_type])) {
            return call_user_func_array($db->options['nativetype_map_callback'][$db_type], array( $db, $field ));
        }
 
        return $this->mapNativeDatatypeInternal($field);
    }
 
 
    abstract protected function mapNativeDatatypeInternal($field);
 
 
    public function mapPrepareDatatype($type)
    {
        $db = $this->getDBInstance();
 
        if (!empty($db->options['datatype_map'][$type])) {
            $type = $db->options['datatype_map'][$type];
            if (!empty($db->options['datatype_map_callback'][$type])) {
                $parameter = array( 'type' => $type );
 
                return call_user_func_array($db->options['datatype_map_callback'][$type], array( &$db, __FUNCTION__, $parameter ));
            }
        }
 
        return $type;
    }
}