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.pgsql.inc, line 420

Database interface code for PostgreSQL database servers.

Code

function db_distinct_field($table, $field, $query) {
  if (!preg_match('/FROM\s+\S+\s+AS/si', $query)
     && !preg_match('/DISTINCT\s+ON\s*\(\s*(' . $table . '\s*\.\s*)?' . $field . '\s*\)/si', $query)
     && !preg_match('/DISTINCT[ (]' . $field . '/si', $query)
     && preg_match('/(.*FROM\s+)(.*?\s)(\s*(WHERE|GROUP|HAVING|ORDER|LIMIT|FOR).*)/Asi', $query, $m)) {
    $query = $m[1];
    $query .= preg_replace('/([\{\w+\}]+)\s+(' . $table . ')\s/Usi', '(SELECT DISTINCT ON (' . $field . ') * FROM \1) \2 ', $m[2]);
    $query .= $m[3];
  }
  return $query;
}