$query.= ', ';
                }
                $query.= 'ADD ' . $db->getDeclaration($field['type'], $field_name, $field);
            }
        }

        if (!empty($changes['remove']) && is_array($changes['remove'])) {
            foreach ($changes['remove'] as $field_name => $field) {
                if ($query) {
                    $query.= ', ';
                }
                $field_name = $db->quoteIdentifier($field_name, true);
                $query.= 'DROP ' . $field_name;
            }
        }

        $rename = array();
        if (!empty($changes['rename']) && is_array($changes['rename'])) {
            foreach ($changes['rename'] as $field_name => $field) {
                $rename[$field['name']] = $field_name;
            }
        }

        if (!empty($changes['change']) && is_array($changes['change'])) {
            foreach ($changes['change'] as $field_name => $field) {
                if ($query) {
                    $query.= ', ';
                }
                if (isset($rename[$field_name])) {
                    $old_field_name = $rename[$field_name];
                    unset($rename[$field_name]);
                } else {
                    $old_field_name = $field_name;
                }
                $old_field_name = $db->quoteIdentifier($old_field_name, true);
                $query.= "CHANGE $old_field_name " . $db->getDeclaration($field['definition']['type'], $field_name, $field['definition']);
            }
        }

        if (!empty($rename) && is_array($rename)) {
            foreach ($rename as $rename_name => $renamed_field) {
                if ($query) {
                    $query.= ', ';
                }
                $field = $changes['rename'][$renamed_field];
                $renamed_field = $db->quoteIdentifier($renamed_field, true);
                $query.= 'CHANGE ' . $renamed_field . ' ' . $db->getDeclaration($field['definition']['type'], $field['name'], $field['definition']);
            }
        }

        if (!$query) {
            return MDB2_OK;
        }

        $name = $db->quoteIdentifier($name, true);
        return $db->exec("ALTER TABLE $name $query");
    }

    // }}}
    // {{{ listDatabases()

    /**
     * list all databases
     *
     * @return mixed array of database names on success, a MDB2 error on failure
     * @access public
     */
    function listDatabases()
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $result = $db->queryCol('SHOW DATABASES');
        if (PEAR::isError($result)) {
            return $result;
        }
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $result = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $result);
        }
        return $result;
    }

    // }}}
    // {{{ listUsers()

    /**
     * list all users
     *
     * @return mixed array of user names on success, a MDB2 error on failure
     * @access public
     */
    function listUsers()
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        return $db->queryCol('SELECT DISTINCT USER FROM mysql.USER');
    }

    // }}}
    // {{{ listFunctions()

    /**
     * list all functions in the current database
     *
     * @return mixed array of function names on success, a MDB2 error on failure
     * @access public
     */
    function listFunctions()
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $query = "SELECT name FROM mysql.proc";
        /*
        SELECT ROUTINE_NAME
          FROM INFORMATION_SCHEMA.ROUTINES
         WHERE ROUTINE_TYPE = 'FUNCTION'
        */
        $result = $db->queryCol($query);
        if (PEAR::isError($result)) {
            return $result;
        }
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $result = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $result);
        }
        return $result;
    }

    // }}}
    // {{{ listTableTriggers()

    /**
     * list all triggers in the database that reference a given table
     *
     * @param string table for which all referenced triggers should be found
     * @return mixed array of trigger names on success, a MDB2 error on failure
     * @access public
     */
    function listTableTriggers($table = null)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $query = 'SHOW TRIGGERS';
        if (!is_null($table)) {
            $table = $db->quote($table, 'text');
            $query .= " LIKE $table";
        }
        $result = $db->queryCol($query);
        if (PEAR::isError($result)) {
            return $result;
        }
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $result = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $result);
        }
        return $result;
    }

    // }}}
    // {{{ listTables()

    /**
     * list all tables in the current database
     *
     * @param string database, the current is default
     * @return mixed array of table names on success, a MDB2 error on failure
     * @access public
     */
    function listTables($database = null)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $query = "SHOW /*!50002 FULL*/ TABLES";
        if (!is_null($database)) {
            $query .= " FROM $database";
        }
        $query.= "/*!50002  WHERE Table_type = 'BASE TABLE'*/";

        $table_names = $db->queryAll($query, null, MDB2_FETCHMODE_ORDERED);
        if (PEAR::isError($table_names)) {
            return $table_names;
        }

        $result = array();
        foreach ($table_names as $table) {
            if (!$this->_fixSequenceName($table[0], true)) {
                $result[] = $table[0];
            }
        }
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $result = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $result);
        }
        return $result;
    }

    // }}}
    // {{{ listViews()

    /**
     * list all views in the current database
     *
     * @param string database, the current is default
     * @return mixed array of view names on success, a MDB2 error on failure
     * @access public
     */
    function listViews($database = null)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $query = 'SHOW FULL TABLES';
        if (!is_null($database)) {
            $query.= " FROM $database";
        }
        $query.= " WHERE Table_type = 'VIEW'";

        $result = $db->queryCol($query);
        if (PEAR::isError($result)) {
            return $result;
        }

        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $result = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $result);
        }
        return $result;
    }

    // }}}
    // {{{ listTableFields()

    /**
     * list all fields in a table in the current database
     *
     * @param string $table name of table that should be used in method
     * @return mixed array of field names on success, a MDB2 error on failure
     * @access public
     */
    function listTableFields($table)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $table = $db->quoteIdentifier($table, true);
        $result = $db->queryCol("SHOW COLUMNS FROM $table");
        if (PEAR::isError($result)) {
            return $result;
        }
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $result = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $result);
        }
        return $result;
    }

    // }}}
    // {{{ createIndex()

    /**
     * Get the stucture of a field into an array
     *
     * @author Leoncx
     * @param string    $table         name of the table on which the index is to be created
     * @param string    $name         name of the index to be created
     * @param array     $definition        associative array that defines properties of the index to be created.
     *                                 Currently, only one property named FIELDS is supported. This property
     *                                 is also an associative with the names of the index fields as array
     *                                 indexes. Each entry of this array is set to another type of associative
     *                                 array that specifies properties of the index that are specific to
     *                                 each field.
     *
     *                                Currently, only the sorting property is supported. It should be used
     *                                 to define the sorting direction of the index. It may be set to either
     *                                 ascending or descending.
     *
     *                                Not all DBMS support index sorting direction configuration. The DBMS
     *                                 drivers of those that do not support it ignore this property. Use the
     *                                 function supports() to determine whether the DBMS driver can manage indexes.
     *
     *                                 Example
     *                                    array(
     *                                        'fields' => array(
     *                                            'user_name' => array(
     *                                                'sorting' => 'ascending'
     *                                                'length' => 10
     *                                            ),
     *                                            'last_login' => array()
     *                                        )
     *                                    )
     * @return mixed MDB2_OK on success, a MDB2 error on failure
     * @access public
     */
    function createIndex($table, $name, $definition)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $table = $db->quoteIdentifier($table, true);
        $name = $db->quoteIdentifier($db->getIndexName($name), true);
        $query = "CREATE INDEX $name ON $table";
        $fields = array();
        foreach ($definition['fields'] as $field => $fieldinfo) {
            if (!empty($fieldinfo['length'])) {
                $fields[] = $db->quoteIdentifier($field, true) . '(' . $fieldinfo['length'] . ')';
            } else {
                $fields[] = $db->quoteIdentifier($field, true);
            }
        }
        $query .= ' ('. implode(', ', $fields) . ')';
        return $db->exec($query);
    }

    // }}}
    // {{{ dropIndex()

    /**
     * drop existing index
     *
     * @param string    $table         name of table that should be used in method
     * @param string    $name         name of the index to be dropped
     * @return mixed MDB2_OK on success, a MDB2 error on failure
     * @access public
     */
    function dropIndex($table, $name)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $table = $db->quoteIdentifier($table, true);
        $name = $db->quoteIdentifier($db->getIndexName($name), true);
        return $db->exec("DROP INDEX $name ON $table");
    }

    // }}}
    // {{{ listTableIndexes()

    /**