db_distinct_field

Versions
4.7 – 6: db_distinct_field($table, $field, $query)

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.

▸ 1 function calls db_distinct_field()

▾ 1 function calls db_distinct_field()

db_rewrite_sql in includes/database.inc: Rewrites node, taxonomy and comment queries. Use it for listing queries. Do not use FROM table1, table2 syntax, use JOIN instead.

Code

includes/database.pgsql.inc, line 375

<?php
function db_distinct_field($table, $field, $query) {
  $field_to_select = 'DISTINCT ON ('. $table .'.'. $field .") $table.$field";
  // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
  $query = preg_replace('/(SELECT.*)('. $table .'\.)?(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1'. $field_to_select .'\3', $query);
  $query = preg_replace('/(ORDER BY )(?!'.$table.'\.'.$field.')/', '\1'."$table.$field, ", $query);
  return $query;
}
?>