MySQL in不走索引
优化前
SELECT*
FROM erp_helei mg WHERE mg.num = 602
AND mg.pid
IN
(10002559,10002561,10002562,10002563,10002564,10002598,10002599,10002600,10002601,10002602,10002603,10002604,10002648,10002649,10002667,10002668,10002676,10002558)优化后
SELECT*
FROM erp_helei mg WHERE mg.num = 602
AND mg.pid
IN
('10002559','10002561','10002562','10002563','10002564','10002598','10002599','10002600','10002601','10002602','10002603','10002604','10002648','10002649','10002667','10002668','10002676','10002558')原因
pid列是char类型，必须加''号才可走索引，否则导致全表扫描，会随着表的增大而变得更慢