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SQL技巧:精妙的SQL语句集中营_MySQL

时间:2021-07-01 10:21:17 帮助过:19人阅读

  精妙的"SQL"语句:

  ◆复制表(只复制结构,源表名:a 新表名:b)

  SQL: select * into b from a where 1<>1

  ◆拷贝表(拷贝数据,源表名:a 目标表名:b)

  SQL: insert into b(a, b, c) select d,e,f from b;

  ◆显示文章、提交人和最后回复时间

  SQL: select a.title,a.username,b.adddate from table a,

  (select max(adddate) adddate from table where table.title=a.title) b

  ◆说明:外连接查询(表名1:a 表名2:b)

  SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a =

  b.c

  ◆日程安排提前五分钟提醒

  SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5

  ◆两张关联表,删除主表中已经在副表中没有的信息

  SQL:

  delete from info where not exists

  ( select * from infobz where info.infid=infobz.infid )

  ◆说明:

  SQL:

  SELECT A.NUM, A.NAME, B.UPD_DATE, B.PREV_UPD_DATE

  FROM TABLE1,(SELECT X.NUM, X.UPD_DATE, Y.UPD_DATE

  PREV_UPD_DATE FROM (SELECT NUM, UPD_DATE, INBOUND_QTY,

  STOCK_ONHAND FROM TABLE2 WHERE TO_CHAR(UPD_DATE,

  'YYYY/MM') = TO_CHAR(SYSDATE, 'YYYY/MM')) X,

  (SELECT NUM, UPD_DATE, STOCK_ONHAND FROM TABLE2

  WHERE TO_CHAR(UPD_DATE,'YYYY/MM') = TO_CHAR(TO_DATE

  (TO_CHAR(SYSDATE, 'YYYY/MM') ¦¦ '/01','

  YYYY/MM/DD') - 1, 'YYYY/MM') ) Y, WHERE X.NUM = Y.NUM

  (+)AND X.INBOUND_QTY + NVL(Y.STOCK_ONHAND,0) <>

  X.STOCK_ONHAND ) B WHERE A.NUM = B.NUM

  ◆说明:

  SQL:

  select * from studentinfo where not exists(select * from student where

  studentinfo.id=student.id) and 系名称='"&strdepartmentname&"' and 专业名称

  ='"&strprofessionname&"' order by 性别,生源地,高考总成绩。

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