mssql.php

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     *
     * @param boolean $check   indicates whether the function should just check if the DBMS driver
     *                         can perform the requested table alterations if the value is true or
     *                         actually perform them otherwise.
     *
     * @return mixed MDB2_OK on success, a MDB2 error on failure
     * @access public
     */
    function alterTable($name, $changes, $check)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }
        $name_quoted = $db->quoteIdentifier($name, true);

        foreach ($changes as $change_name => $change) {
            switch ($change_name) {
            case 'remove':
            case 'rename':
            case 'add':
            case 'change':
            case 'name':
                break;
            default:
                return $db->raiseError(MDB2_ERROR_CANNOT_ALTER, null, null,
                    'change type "'.$change_name.'" not yet supported', __FUNCTION__);
            }
        }

        if ($check) {
            return MDB2_OK;
        }

        $idxname_format = $db->getOption('idxname_format');
        $db->setOption('idxname_format', '%s');

        if (!empty($changes['remove']) && is_array($changes['remove'])) {
            $result = $this->_dropConflictingIndices($name, array_keys($changes['remove']));
            if (PEAR::isError($result)) {
                $db->setOption('idxname_format', $idxname_format);
                return $result;
            }
            $result = $this->_dropConflictingConstraints($name, array_keys($changes['remove']));
            if (PEAR::isError($result)) {
                $db->setOption('idxname_format', $idxname_format);
                return $result;
            }

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

            $result = $db->exec("ALTER TABLE $name_quoted DROP $query");
            if (PEAR::isError($result)) {
                $db->setOption('idxname_format', $idxname_format);
                return $result;
            }
        }

        if (!empty($changes['rename']) && is_array($changes['rename'])) {
            foreach ($changes['rename'] as $field_name => $field) {
                $field_name = $db->quoteIdentifier($field_name, true);
                $result = $db->exec("sp_rename '$name_quoted.$field_name', '".$field['name']."', 'COLUMN'");
                if (PEAR::isError($result)) {
                    $db->setOption('idxname_format', $idxname_format);
                    return $result;
                }
            }
        }

        if (!empty($changes['add']) && is_array($changes['add'])) {
            $query = '';
            foreach ($changes['add'] as $field_name => $field) {
                if ($query) {
                    $query.= ', ';
                } else {
                    $query.= 'ADD ';
                }
                $query.= $db->getDeclaration($field['type'], $field_name, $field);
            }

            $result = $db->exec("ALTER TABLE $name_quoted $query");
            if (PEAR::isError($result)) {
                $db->setOption('idxname_format', $idxname_format);
                return $result;
            }
        }

        $dropped_indices     = array();
        $dropped_constraints = array();

        if (!empty($changes['change']) && is_array($changes['change'])) {
            $dropped = $this->_dropConflictingIndices($name, array_keys($changes['change']));
            if (PEAR::isError($dropped)) {
                $db->setOption('idxname_format', $idxname_format);
                return $dropped;
            }
            $dropped_indices = array_merge($dropped_indices, $dropped);
            $dropped = $this->_dropConflictingConstraints($name, array_keys($changes['change']));
            if (PEAR::isError($dropped)) {
                $db->setOption('idxname_format', $idxname_format);
                return $dropped;
            }
            $dropped_constraints = array_merge($dropped_constraints, $dropped);

            foreach ($changes['change'] as $field_name => $field) {
                //MSSQL doesn't allow multiple ALTER COLUMNs in one query
                $query = 'ALTER COLUMN ';

                //MSSQL doesn't allow changing the DEFAULT value of a field in altering mode
                if (array_key_exists('default', $field['definition'])) {
                    unset($field['definition']['default']);
                }

                $query .= $db->getDeclaration($field['definition']['type'], $field_name, $field['definition']);
                $result = $db->exec("ALTER TABLE $name_quoted $query");
                if (PEAR::isError($result)) {
                    $db->setOption('idxname_format', $idxname_format);
                    return $result;
                }
            }
        }

        // restore the dropped conflicting indices and constraints
        foreach ($dropped_indices as $index_name => $index) {
            $result = $this->createIndex($name, $index_name, $index);
            if (PEAR::isError($result)) {
                $db->setOption('idxname_format', $idxname_format);
                return $result;
            }
        }
        foreach ($dropped_constraints as $constraint_name => $constraint) {
            $result = $this->createConstraint($name, $constraint_name, $constraint);
            if (PEAR::isError($result)) {
                $db->setOption('idxname_format', $idxname_format);
                return $result;
            }
        }

        $db->setOption('idxname_format', $idxname_format);

        if (!empty($changes['name'])) {
            $new_name = $db->quoteIdentifier($changes['name'], true);
            $result = $db->exec("sp_rename '$name_quoted', '$new_name'");
            if (PEAR::isError($result)) {
                return $result;
            }
        }

        return MDB2_OK;
    }

    // }}}
    // {{{ _dropConflictingIndices()

    /**
     * Drop the indices that prevent a successful ALTER TABLE action
     *
     * @param string $table  table name
     * @param array  $fields array of names of the fields affected by the change
     *
     * @return array dropped indices definitions
     */
    function _dropConflictingIndices($table, $fields)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $dropped = array();
        $index_names = $this->listTableIndexes($table);
        if (PEAR::isError($index_names)) {
            return $index_names;
        }
        $db->loadModule('Reverse');
        $indexes = array();
        foreach ($index_names as $index_name) {
        	$idx_def = $db->reverse->getTableIndexDefinition($table, $index_name);
            if (!PEAR::isError($idx_def)) {
                $indexes[$index_name] = $idx_def;
            }
        }
        foreach ($fields as $field_name) {
            foreach ($indexes as $index_name => $index) {
                if (!isset($dropped[$index_name]) && array_key_exists($field_name, $index['fields'])) {
                    $dropped[$index_name] = $index;
                    $result = $this->dropIndex($table, $index_name);
                    if (PEAR::isError($result)) {
                        return $result;
                    }
                }
            }
        }

        return $dropped;
    }

    // }}}
    // {{{ _dropConflictingConstraints()

    /**
     * Drop the constraints that prevent a successful ALTER TABLE action
     *
     * @param string $table  table name
     * @param array  $fields array of names of the fields affected by the change
     *
     * @return array dropped constraints definitions
     */
    function _dropConflictingConstraints($table, $fields)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $dropped = array();
        $constraint_names = $this->listTableConstraints($table);
        if (PEAR::isError($constraint_names)) {
            return $constraint_names;
        }
        $db->loadModule('Reverse');
        $constraints = array();
        foreach ($constraint_names as $constraint_name) {
        	$cons_def = $db->reverse->getTableConstraintDefinition($table, $constraint_name);
            if (!PEAR::isError($cons_def)) {
                $constraints[$constraint_name] = $cons_def;
            }
        }
        foreach ($fields as $field_name) {
            foreach ($constraints as $constraint_name => $constraint) {
                if (!isset($dropped[$constraint_name]) && array_key_exists($field_name, $constraint['fields'])) {
                    $dropped[$constraint_name] = $constraint;
                    $result = $this->dropConstraint($table, $constraint_name);
                    if (PEAR::isError($result)) {
                        return $result;
                    }
                }
            }
            // also drop implicit DEFAULT constraints
            $default = $this->_getTableFieldDefaultConstraint($table, $field_name);
            if (!PEAR::isError($default) && !empty($default)) {
                $result = $this->dropConstraint($table, $default);
                if (PEAR::isError($result)) {
                    return $result;
                }
            }
        }

        return $dropped;
    }

    // }}}
    // {{{ _getTableFieldDefaultConstraint()

    /**
     * Get the default constraint for a table field
     *
     * @param string $table name of table that should be used in method
     * @param string $field name of field that should be used in method
     *
     * @return mixed name of default constraint on success, a MDB2 error on failure
     * @access private
     */
    function _getTableFieldDefaultConstraint($table, $field)
    {
        $db =& $this->getDBInstance();
        if (PEAR::isError($db)) {
            return $db;
        }

        $table = $db->quoteIdentifier($table, true);
        $field = $db->quote($field, 'text');
        $query = "SELECT OBJECT_NAME(syscolumns.cdefault)
                    FROM syscolumns
                   WHERE syscolumns.id = object_id('$table')
                     AND syscolumns.name = $field
                     AND syscolumns.cdefault <> 0";
        return $db->queryOne($query);
    }

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

    /**
     * list all tables in the current database
     *
     * @return mixed array of table names on success, a MDB2 error on failure
     * @access public
     */
    function listTables()
    {
        $db =& $this->getDBInstance();

        if (PEAR::isError($db)) {
            return $db;
        }

        $query = 'EXEC sp_tables @table_type = "\'TABLE\'"';
        $table_names = $db->queryCol($query, null, 2);
        if (PEAR::isError($table_names)) {
            return $table_names;
        }
        $result = array();
        foreach ($table_names as $table_name) {
            if (!$this->_fixSequenceName($table_name, true)) {
                $result[] = $table_name;
            }
        }
        if ($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);
        $columns = $db->queryCol("SELECT c.name
                                    FROM syscolumns c
                               LEFT JOIN sysobjects o ON c.id = o.id
                                   WHERE o.name = '$table'");
        if (PEAR::isError($columns)) {
            return $columns;
        }
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            $columns = array_map(($db->options['field_case'] == CASE_LOWER ? 'strtolower' : 'strtoupper'), $columns);
        }
        return $columns;
    }

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

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

        $key_name = 'INDEX_NAME';
        $pk_name = 'PK_NAME';
        if ($db->options['portability'] & MDB2_PORTABILITY_FIX_CASE) {
            if ($db->options['field_case'] == CASE_LOWER) {
                $key_name = strtolower($key_name);