精妙SQL语句精华

　　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)