height 为int(非主键) 使用in 会导致索引失效 还有 != ,<>,not in 导致索引失效
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;