高手是怎样炼成的:精妙SQL语句介绍
类别: 数据库教程 
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。本文收集了部分比较经典，常用的SQL语句供大家参考，希望对大家有所帮助。
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)
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)
