Same name in this branch
  1. 5.x includes/database.pgsql.inc \db_distinct_field()
  2. 5.x includes/database.mysqli.inc \db_distinct_field()
  3. 5.x includes/database.mysql.inc \db_distinct_field()
Same name and namespace in other branches
  1. 4.7.x includes/database.pgsql.inc \db_distinct_field()
  2. 4.7.x includes/database.mysqli.inc \db_distinct_field()
  3. 4.7.x includes/database.mysql.inc \db_distinct_field()
  4. 6.x includes/database.inc \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()
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.

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;
}