之前做过一个测试: select id,title from ** 与select * from **的速度测试。 这是后续版. 测试的结果是: [st@localhost test]$ php select.php cost1:2.1355810165405 cost2:2.5820469856262 [st@localhost test]$ php select.php cost1:1.9796178340912 cost2:2.5190000534058 [st@localhost test]$ php select.php cost1:1.9672379493713 cost2:2.9030020236969 [st@localhost test]$ php select.php cost1:1.9810240268707 cost2:2.5505940914154 好了,现在将SQL1和SQL2次序交换: calhost test]$ php select.php cost1:2.5933158397675 cost2:2.0362050533295 [st@localhost test]$ php select.php cost1:2.6104090213776 cost2:2.056037902832 [st@localhost test]$ php select.php cost1:4.2802629470825 cost2:3.3958988189697 [st@localhost test]$ php select.php cost1:2.6283531188965 cost2:2.0102050304413 大体上,SELECT COL1,COL2,COL3….. 与SELECT * 相比,两者花费的时间之比是4:5.不知道非空表的结果会不会是这样?