摘要:
一、首先说一下我的需求,在数据表T_CERTI_EXELAW中求certicode字段前三位出现次数最多的三位(期望结果是207),数据表如下: 期望结果是207二、两种sql语句比较(oracle数据库)方法一:常规嵌套(耗时:0.031seconds)SELECT NAME FROM (SELECT HEAD AS NAME, COUNT(HEAD) AS TIMES FROM (SELECT SUBSTR(M.CERTICODE, 0, 3) AS HEAD FROM T_CERTI_EXELAW M WHERE M.MAKEDEPART = ... 阅读全文
摘要:
For many times,i've given my own a new lifestyle,such as don't stay up late,have breakfast......while actually it didn't work ,i come to suspect the ability of control,maybe it is not the point to change ,but at then i'll be a loser, who can help me ? who can? ... nobody, it's me 阅读全文