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精妙SQL语句介绍


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#1 稻草人

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发表于 2007/02/24 23:58:43

如何从一位菜鸟蜕变成为高手,灵活使用的SQL语句是必不可少的。
  说明: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

  说明: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;

  说明: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

  说明: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  

  说明: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

  说明:

  从数据库中去一年的各单位电话费统计(电话费定额贺电化肥清单两个表来源)

  SQL:  

  SELECT a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, 'yyyy') AS telyear,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '01', a.factration)) AS JAN,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '02', a.factration)) AS FRI,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '03', a.factration)) AS MAR,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '04', a.factration)) AS APR,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '05', a.factration)) AS MAY,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '06', a.factration)) AS JUE,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '07', a.factration)) AS JUL,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '08', a.factration)) AS AGU,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '09', a.factration)) AS SEP,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '10', a.factration)) AS OCT,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '11', a.factration)) AS NOV,

   SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '12', a.factration)) AS DEC

  FROM (SELECT a.userper, a.tel, a.standfee, b.telfeedate, b.factration

   FROM TELFEESTAND a, TELFEE b

   WHERE a.tel = b.telfax) a

  GROUP BY a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, 'yyyy')

  说明:四表联查问题:  

  SQL: select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where .....

  说明:得到表中最小的未使用的ID号

  SQL: 

  SELECT (CASE WHEN EXISTS(SELECT * FROM Handle b WHERE b.HandleID = 1) THEN MIN(HandleID) + 1 ELSE 1 END) as HandleID

   FROM Handle

   WHERE NOT HandleID IN (SELECT a.HandleID - 1 FROM Handle a)