SQL高手篇：精妙SQL语句说明介绍

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　　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)

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