SQL中索引失效列子

height 爲int（非主鍵）  使用in 會導致索引失效   還有 ！=  ,<>,not in 導致索引失效

EXPLAIN SELECT id, name ,age FROM vtiger_knowledgess WHERE height IN('122','11');
EXPLAIN SELECT id, name ,age FROM vtiger_knowledgess WHERE height IN(122,11);
EXPLAIN SELECT id, name ,age FROM vtiger_knowledgess WHERE height NOT IN(122,11);
EXPLAIN SELECT id, name ,age FROM vtiger_knowledgess WHERE height !=122;
EXPLAIN SELECT id, name ,age FROM vtiger_knowledgess WHERE height <>122;