- Patch #98059 by chx: trying to get the never-ending regex mess right.

includes/database.mysql.inc

@@ -431,7 +431,7 @@ function db_table_exists($table) {
 function db_distinct_field($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);
+  return preg_replace('/(SELECT.*)(?:'. $table .'\.|\s)(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1 '. $field_to_select .'\2', $query);
 }
 
 /**

includes/database.mysqli.inc

@@ -416,7 +416,7 @@ function db_table_exists($table) {
 function db_distinct_field($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);
+  return preg_replace('/(SELECT.*)(?:'. $table .'\.|\s)(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1 '. $field_to_select .'\2', $query);
 }
 
 /**

includes/database.pgsql.inc

@@ -414,7 +414,7 @@ function db_check_setup() {
 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('/(SELECT.*)(?:'. $table .'\.|\s)(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1 '. $field_to_select .'\2', $query);
   $query = preg_replace('/(ORDER BY )(?!'.$table.'\.'.$field.')/', '\1'."$table.$field, ", $query);
   return $query;
 }