addField('t', 'id', 'id'); $subquery->condition('age', 28, '<'); $query = db_select('test', 't'); $query->addField('t', 'name', 'name'); $query->condition('id', $subquery, 'IN'); $clone = clone $query; // Cloned query should not be altered by the following modification // happening on original query. $subquery->condition('age', 25, '>'); $clone_result = $clone->countQuery()->execute()->fetchField(); $query_result = $query->countQuery()->execute()->fetchField(); // Make sure the cloned query has not been modified $this->assertEqual(3, $clone_result, 'The cloned query returns the expected number of rows'); $this->assertEqual(2, $query_result, 'The query returns the expected number of rows'); } }