select distinct 院系编号=substring(stud_id,4,2) from stud_info 是什么意思

select distinct 院系编号=substring(stud_id,4,2) from stud_info 是什么意思 distinct 这句SQL语句是什么意思.ql=select distinct(selabel) from.sql=select distinct(selabel) from kcwl_labprosellog where isdel=0 &sqlfile& and selabel not in (select distinct(selabel) from kcwl_labprosell) 这个语句是什么作用的.说具 select telnum,count(0),count(distinct othertelnum) from nmk.ljdx_cdr_temp group by telnum SQL里的DISTINCT什么意思SELECT Sno,AVG(Grade)FROM SCGROUP BY SnoHAVING COUNT(DISTINCT(Sno))>1;既然已经按Sno分类了,再用DISTINCT那HAVING COUNT(DISTINCT(Sno))的值岂不是只能为1? 请问sql语句“Select Distinct”是什么意思?可不可以讲一下它的用法1.Select Distinct 货品编码,数量 From 订单信息2.Select Distinct 货品编码 From 订单信息第一句和第二句有什么分别,请高手说说Distinct select * from order where clientNo in (select distinct(clientNo) from orders ) 转化为HQL怎么写?order是表名 clientNo是其中一个列名!怎么转换成HQL, 大侠这个查询语句的意思是什么?sql=select DISTINCT 日期 from +tablename+ where 日期>=' +df +' and 日期 select distinct id from names where tid = 'AREACODE' And dsc like '%' || v_areacode其中dsc like '%' || v_areacode sql如何取交集有这样两条sql语句select distinct id from a where id='123'select distinct id from a where id='456'我希望能把他们取得他们记录的交集,sql语句该如何写?错了 应该是这样的select distinct temid from a whe SELECT group by 和 distinct 的问题select a.partner as pcode, count(distinct(a.deviceid)) as count -- into num4 from test a where a.activationtime >= to_date('2011-4-17', 'yyyy-mm-dd') and a.activationtime < to_date( selectT_customer.customer_No,customer_Name,customer_Category,customer_State,customer_Tel,customer_InputeDate,trackrecord_DateTime=null,days=null from T_customer where T_customer.customer_No not in(select distinct customer_No from T_trackrecord) 至 大侠这个查询语句的意思?大侠这个查询语句的意思是什么?sql=select DISTINCT 日期 from +tablename+ where 日期>=' +df +' and 日期 select min(name) from tableselect * from table where id in (select min(id) from table group by name)那这样的话我是不是可以理解为他可以 完成 DISTINCT一样的效果呢? DISTINCT是什么意思 SQL语句中的 Distinct 和 Group by 有什么不同,用那个好?select Distinct 品名,单位 from [表]和select 品名,单位 from [表]Group by 品名,单位查询的结果是一样的,都是把相同的记录合并为一条,这两个有什么 select distinct A.* from A,B where A.id = B.g_id and A.fwzid = 2 我那个地方是写的 select distinct A.* from A,B where A.id B.g_id and A.fwzid = 2 好像就会出错,