diff options
Diffstat (limited to 'includes/database.mysqli.inc')
| -rw-r--r-- | includes/database.mysqli.inc | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/includes/database.mysqli.inc b/includes/database.mysqli.inc index 7cc5943b7..7e9ba9dcb 100644 --- a/includes/database.mysqli.inc +++ b/includes/database.mysqli.inc @@ -413,6 +413,23 @@ function db_table_exists($table) { } /** + * Wraps the given table.field entry with a DISTINCT(). The wrapper is added to + * the SELECT list entry of the given query and the resulting query is returned. + * This function only applies the wrapper if a DISTINCT doesn't already exist in + * the query. + * + * @param $table Table containing the field to set as DISTINCT + * @param $field Field to set as DISTINCT + * @param $query Query to apply the wrapper to + * @return SQL query with the DISTINCT wrapper surrounding the given table.field. + */ +function db_distinct_field($table, $field, $query) { + $field_to_select = 'DISTINCT('. $table .'.'. $field .')'; + // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT). + return preg_replace('/(SELECT.*)('. $table .'\.)?(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1'. $field_to_select .'\3', $query); +} + +/** * @} End of "ingroup database". */ |