select id, taskcode,polcode,ricode,insuredcode,caltypecode,productcode,polyear,contcode,ritype,premtype,instcode,firsttermflag,caldate,inexflag,deleteflag,effectflag,rpttempcode,creator,res2 from cal_premium where rpttempcode in ('TCRC2120060722011011', 'TCRC2120060722011015', 'TCRC2120060722011023', 'TCRC2120060722011027', 'TCRC2120060722011029', 'TCRC2120060722011035', 'TCRC2120060722011036', 'TCRC2120060722011039', 'TCRC2120060722011041', 'TCRC2120060722011043', 'TCRC2120060722011053', 'TCRC2120060722011056', 'TCRC2120060722011073', 'TCRC2120060722011075', 'TCRC2120060722011007', 'TCRC2120060722011031', 'TCRC2120060722011051', 'TCRC2120060722011025', 'TCRC2120060722011055', 'TCRC2120060722011019', 'TCRC2120060722011059', 'TCRC2120060722011065', 'TCRC2120060722011069', 'TCRC2120060722011005', 'TCRC2120060722011013', 'TCRC2120060722011017', 'TCRC2120060722011033', 'TCRC2120060722011071', 'TCRC2120060722011021', 'TCRC2120060722011049', 'TCRC2120060722011045', 'TCRC2120060722011047', 'TCRC2120060722011009', 'TCRC2120060722011067', 'TCRC2120060722011063') and productcode in ('S51') and caltypecode in ('PC') and firsttermflag='FO' and deleteflag='F' order by caltypecode,id asc
怎么优化一下 这语句?
怎么优化一下 这语句?
(SELECT CUSTOMER_NAME FROM CUSTOMER)优化
SELECT * FROM ORDERS WHERE CUSTOMER_NAME not exist
(SELECT CUSTOMER_NAME FROM CUSTOMER)
and productcode in ('S51') and caltypecode in ('PC')
如果能用exists替代in的情况下为什么不替代呢?
(2)不知道你索引是怎么建的?,如果执行效率不高的话,应该是索引建的有问题。把索引帖出来,我帮你看看。
但是不同的数据库未必都表现出这样的情形我就碰到过一条in的语句,在oracle中执行需要1分多种,但在db2中仅需几秒
一些特殊情况的存在,也需要在相同数据,相同的表结构,相同数据库下测试才准确啊。。参考不一样,能证明什么?