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摘要：
1、使用where语句不推荐Select * from zflight.Check : zflight-airln = ‘LF’ and zflight-fligh = ‘BW222’.Endselect.推荐Select * from zflight where airln = ‘LF’ and fligh = ‘222’.Endselect.2、使用聚合函数不推荐Maxnu = 0.Select * from zflight where airln = ‘LF’ and cntry = ‘IN’.Check zflight-fligh > maxnu.Maxnu = zflight- 阅读全文