db2.php

Bug tracker, and reporter.

     * PRIMARY          => boolean; true if column is part of the primary key
     * PRIMARY_POSITION => integer; position of column in primary key
     * IDENTITY         => integer; true if column is auto-generated with unique values
     *
     * @todo Discover integer unsigned property.
     *
     * @param string $tableName
     * @param string $schemaName OPTIONAL
     * @return array
     */
    public function describeTable($tableName, $schemaName = null)
    {
        $sql = "SELECT DISTINCT c.tabschema, c.tabname, c.colname, c.colno,
              c.typename, c.default, c.nulls, c.length, c.scale,
              c.identity, tc.type AS tabconsttype, k.colseq
            FROM syscat.columns c
              LEFT JOIN (syscat.keycoluse k JOIN syscat.tabconst tc
                ON (k.tabschema = tc.tabschema
                  AND k.tabname = tc.tabname
                  AND tc.type = 'P'))
              ON (c.tabschema = k.tabschema
                AND c.tabname = k.tabname
                AND c.colname = k.colname)
            WHERE "
            . $this->quoteInto('UPPER(c.tabname) = UPPER(?)', $tableName);
        if ($schemaName) {
            $sql .= $this->quoteInto(' AND UPPER(c.tabschema) = UPPER(?)', $schemaName);
        }
        $sql .= " ORDER BY c.colno";

        $desc = array();
        $stmt = $this->query($sql);

        /**
         * To avoid case issues, fetch using FETCH_NUM
         */
        $result = $stmt->fetchAll(Zend_Db::FETCH_NUM);

        /**
         * The ordering of columns is defined by the query so we can map
         * to variables to improve readability
         */
        $tabschema      = 0;
        $tabname        = 1;
        $colname        = 2;
        $colno          = 3;
        $typename       = 4;
        $default        = 5;
        $nulls          = 6;
        $length         = 7;
        $scale          = 8;
        $identityCol    = 9;
        $tabconstype    = 10;
        $colseq         = 11;

        foreach ($result as $key => $row) {
            list ($primary, $primaryPosition, $identity) = array(false, null, false);
            if ($row[$tabconstype] == 'P') {
                $primary = true;
                $primaryPosition = $row[$colseq];
            }
            /**
             * In IBM DB2, an column can be IDENTITY
             * even if it is not part of the PRIMARY KEY.
             */
            if ($row[$identityCol] == 'Y') {
                $identity = true;
            }

            // only colname needs to be case adjusted
            $desc[$this->foldCase($row[$colname])] = array(
                'SCHEMA_NAME'      => $this->foldCase($row[$tabschema]),
                'TABLE_NAME'       => $this->foldCase($row[$tabname]),
                'COLUMN_NAME'      => $this->foldCase($row[$colname]),
                'COLUMN_POSITION'  => $row[$colno]+1,
                'DATA_TYPE'        => $row[$typename],
                'DEFAULT'          => $row[$default],
                'NULLABLE'         => (bool) ($row[$nulls] == 'Y'),
                'LENGTH'           => $row[$length],
                'SCALE'            => $row[$scale],
                'PRECISION'        => ($row[$typename] == 'DECIMAL' ? $row[$length] : 0),
                'UNSIGNED'         => null, // @todo
                'PRIMARY'          => $primary,
                'PRIMARY_POSITION' => $primaryPosition,
                'IDENTITY'         => $identity
            );
        }

        return $desc;
    }

    /**
     * Return the most recent value from the specified sequence in the database.
     * This is supported only on RDBMS brands that support sequences
     * (e.g. Oracle, PostgreSQL, DB2).  Other RDBMS brands return null.
     *
     * @param string $sequenceName
     * @return string
     */
    public function lastSequenceId($sequenceName)
    {
        $this->_connect();
        $sql = 'SELECT PREVVAL FOR '.$this->quoteIdentifier($sequenceName, true).' AS VAL FROM SYSIBM.SYSDUMMY1';
        $value = $this->fetchOne($sql);
        return (string) $value;
    }

    /**
     * Generate a new value from the specified sequence in the database, and return it.
     * This is supported only on RDBMS brands that support sequences
     * (e.g. Oracle, PostgreSQL, DB2).  Other RDBMS brands return null.
     *
     * @param string $sequenceName
     * @return string
     */
    public function nextSequenceId($sequenceName)
    {
        $this->_connect();
        $sql = 'SELECT NEXTVAL FOR '.$this->quoteIdentifier($sequenceName, true).' AS VAL FROM SYSIBM.SYSDUMMY1';
        $value = $this->fetchOne($sql);
        return (string) $value;
    }

    /**
     * Gets the last ID generated automatically by an IDENTITY/AUTOINCREMENT column.
     *
     * As a convention, on RDBMS brands that support sequences
     * (e.g. Oracle, PostgreSQL, DB2), this method forms the name of a sequence
     * from the arguments and returns the last id generated by that sequence.
     * On RDBMS brands that support IDENTITY/AUTOINCREMENT columns, this method
     * returns the last value generated for such a column, and the table name
     * argument is disregarded.
     *
     * The IDENTITY_VAL_LOCAL() function gives the last generated identity value
     * in the current process, even if it was for a GENERATED column.
     *
     * @param string $tableName OPTIONAL
     * @param string $primaryKey OPTIONAL
     * @return string
     */
    public function lastInsertId($tableName = null, $primaryKey = null)
    {
        $this->_connect();

        if ($tableName !== null) {
            $sequenceName = $tableName;
            if ($primaryKey) {
                $sequenceName .= "_$primaryKey";
            }
            $sequenceName .= '_seq';
            return $this->lastSequenceId($sequenceName);
        }

        $sql = 'SELECT IDENTITY_VAL_LOCAL() AS VAL FROM SYSIBM.SYSDUMMY1';
        $value = $this->fetchOne($sql);
        return (string) $value;
    }

    /**
     * Begin a transaction.
     *
     * @return void
     */
    protected function _beginTransaction()
    {
        $this->_setExecuteMode(DB2_AUTOCOMMIT_OFF);
    }

    /**
     * Commit a transaction.
     *
     * @return void
     */
    protected function _commit()
    {
        if (!db2_commit($this->_connection)) {
            /**
             * @see Zend_Db_Adapter_Db2_Exception
             */
            require_once 'Zend/Db/Adapter/Db2/Exception.php';
            throw new Zend_Db_Adapter_Db2_Exception(
                db2_conn_errormsg($this->_connection),
                db2_conn_error($this->_connection));
        }

        $this->_setExecuteMode(DB2_AUTOCOMMIT_ON);
    }

    /**
     * Rollback a transaction.
     *
     * @return void
     */
    protected function _rollBack()
    {
        if (!db2_rollback($this->_connection)) {
            /**
             * @see Zend_Db_Adapter_Db2_Exception
             */
            require_once 'Zend/Db/Adapter/Db2/Exception.php';
            throw new Zend_Db_Adapter_Db2_Exception(
                db2_conn_errormsg($this->_connection),
                db2_conn_error($this->_connection));
        }
        $this->_setExecuteMode(DB2_AUTOCOMMIT_ON);
    }

    /**
     * Set the fetch mode.
     *
     * @param integer $mode
     * @return void
     * @throws Zend_Db_Adapter_Db2_Exception
     */
    public function setFetchMode($mode)
    {
        switch ($mode) {
            case Zend_Db::FETCH_NUM:   // seq array
            case Zend_Db::FETCH_ASSOC: // assoc array
            case Zend_Db::FETCH_BOTH:  // seq+assoc array
            case Zend_Db::FETCH_OBJ:   // object
                $this->_fetchMode = $mode;
                break;
            case Zend_Db::FETCH_BOUND:   // bound to PHP variable
                /**
                 * @see Zend_Db_Adapter_Db2_Exception
                 */
                require_once 'Zend/Db/Adapter/Db2/Exception.php';
                throw new Zend_Db_Adapter_Db2_Exception('FETCH_BOUND is not supported yet');
                break;
            default:
                /**
                 * @see Zend_Db_Adapter_Db2_Exception
                 */
                require_once 'Zend/Db/Adapter/Db2/Exception.php';
                throw new Zend_Db_Adapter_Db2_Exception("Invalid fetch mode '$mode' specified");
                break;
        }
    }

    /**
     * Adds an adapter-specific LIMIT clause to the SELECT statement.
     *
     * @param string $sql
     * @param integer $count
     * @param integer $offset OPTIONAL
     * @return string
     */
    public function limit($sql, $count, $offset = 0)
    {
        $count = intval($count);
        if ($count <= 0) {
            /**
             * @see Zend_Db_Adapter_Db2_Exception
             */
            require_once 'Zend/Db/Adapter/Db2/Exception.php';
            throw new Zend_Db_Adapter_Db2_Exception("LIMIT argument count=$count is not valid");
        }

        $offset = intval($offset);
        if ($offset < 0) {
            /**
             * @see Zend_Db_Adapter_Db2_Exception
             */
            require_once 'Zend/Db/Adapter/Db2/Exception.php';
            throw new Zend_Db_Adapter_Db2_Exception("LIMIT argument offset=$offset is not valid");
        }

        if ($offset == 0) {
            $limit_sql = $sql . " FETCH FIRST $count ROWS ONLY";
            return $limit_sql;
        }

        /**
         * DB2 does not implement the LIMIT clause as some RDBMS do.
         * We have to simulate it with subqueries and ROWNUM.
         * Unfortunately because we use the column wildcard "*",
         * this puts an extra column into the query result set.
         */
        $limit_sql = "SELECT z2.*
            FROM (
                SELECT ROW_NUMBER() OVER() AS \"ZEND_DB_ROWNUM\", z1.*
                FROM (
                    " . $sql . "
                ) z1
            ) z2
            WHERE z2.zend_db_rownum BETWEEN " . ($offset+1) . " AND " . ($offset+$count);
        return $limit_sql;
    }

    /**
     * Check if the adapter supports real SQL parameters.
     *
     * @param string $type 'positional' or 'named'
     * @return bool
     */
    public function supportsParameters($type)
    {
        switch ($type) {
            case 'positional':
                return true;
            case 'named':
            default:
                return false;
        }
    }

}