db_rewrite_sql
Definition
db_rewrite_sql($query, $primary_table = 'n', $primary_field = 'nid', $args = array())
drupal/includes/database/database.inc, line 2442
Description
Rewrites node, taxonomy and comment queries. Use it for listing queries. Do not use FROM table1, table2 syntax, use JOIN instead.
@todo Remove this function when all code has been converted to query_alter.
Parameters
$query Query to be rewritten.
$primary_table Name or alias of the table which has the primary key field for this query. Typical table names would be: {block}, {comment}, {forum}, {node}, {menu}, {term_data} or {vocabulary}. However, it is more common to use the the usual table aliases: b, c, f, n, m, t or v.
$primary_field Name of the primary field.
$args An array of arguments, passed to the implementations of hook_db_rewrite_sql.
Return value
The original query with JOIN and WHERE statements inserted from hook_db_rewrite_sql implementations. nid is rewritten if needed.
Related topics
Name | Description |
|---|---|
| Database abstraction layer | Allow the use of different database servers using the same code base. |
Code
function db_rewrite_sql($query, $primary_table = 'n', $primary_field = 'nid', $args = array()) {
list($join, $where, $distinct) = _db_rewrite_sql($query, $primary_table, $primary_field, $args);
if ($distinct) {
$query = db_distinct_field($primary_table, $primary_field, $query);
}
if (!empty($where) || !empty($join)) {
$pattern = '{
# Beginning of the string
^
((?P<anonymous_view>
# Everything within this set of parentheses is named "anonymous view"
(?:
[^()]++ # anything not parentheses
|
\( (?P>anonymous_view) \) # an open parenthesis, more "anonymous view" and finally a close parenthesis.
)*
)[^()]+WHERE)
}x';
preg_match($pattern, $query, $matches);
if ($where) {
$n = strlen($matches[1]);
$second_part = substr($query, $n);
$first_part = substr($matches[1], 0, $n - 5) ." $join WHERE $where AND ( ";
foreach (array('GROUP', 'ORDER', 'LIMIT') as $needle) {
$pos = strrpos($second_part, $needle);
if ($pos !== FALSE) {
// All needles are five characters long.
$pos += 5;
break;
}
}
if ($pos === FALSE) {
$query = $first_part . $second_part . ')';
}
else {
$query = $first_part . substr($second_part, 0, -$pos) . ')' . substr($second_part, -$pos);
}
}
else {
$query = $matches[1] . " $join " . substr($query, strlen($matches[1]));
}
}
return $query;
}