db_distinct_field

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

Database abstraction layer

Allow the use of different database servers using the same code base.

1 call to db_distinct_field()

File

includes/database.mysql.inc, line 436

Database interface code for MySQL database servers.

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 . '\.|\s)(?<!DISTINCT\()(?<!DISTINCT\(' . $table . '\.)' . $field . '(.*FROM )/AUsi', '\1 ' . $field_to_select . '\2', $query);
}