db_distinct_field
Definition
db_distinct_field($table, $field, $query)
drupal/includes/database.mysqli.inc, line 364
Description
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.
Parameters
$table Table containing the field to set as DISTINCT
$field Field to set as DISTINCT
$query Query to apply the wrapper to
Return value
SQL query with the DISTINCT wrapper surrounding the given table.field.
Related topics
Name | Description |
|---|---|
| Database abstraction layer | Allow the use of different database servers using the same code base. |
Code
function db_distinct_field($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);
}