最新回答 / weixin_慕工程1563154
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2019-08-02
最新回答 / 慕沐6523080
select ci_id,MAX(M) from (select ci_id,wm_concat(stu_name) over (partition by c.ci_id order by s.stu_id)m from pm_ci c,pm_stu s where instr(c.stu_ids,s.stu_id)>0)e group by e.ci_id;
2019-06-27
已采纳回答 / Johnny_t
select 1 from dual where null != null;select 1 from dual where null is null;
2019-04-25
已采纳回答 / Amousy
<...code...>用distinct可以找到不重复记录，
select distinct mgr from emp where mgr is not null;上面这条语句的功能可以找到所有老板。很明显King（7839）是包括在里面的，为什么select * from e...
2019-03-24
最赞回答 / 大王叫我来巡山570127
1、先创建表及初始化数据 ①创建及初始化学生表PM_STUcreate table PM_STU(STU_ID VARCHAR2(20) NOT NULL, STU_NAME VARCHAR2(20)); INSERT INTO PM_STU VALUES(1,'张三');INSERT INTO PM_STU VALUES(2,'李四');INSERT INTO PM_STU...
2019-01-06