精妙SQL語句（轉帖）

說明：複制表(隻複制結構,源表名：a 新表名：b)

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

說明：拷貝表(拷貝資料,源表名：a 目标表名：b)

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

說明：顯示文章、送出人和最後回複時間 SQL: select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b

說明：外連接配接查詢(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

說明：日程安排提前五分鐘提醒

SQL: select * from 日程安排 where datediff('minute',f開始時間,getdate())>5

說明：兩張關聯表，删除主表中已經在副表中沒有的資訊

SQL:

delete from info where not exists ( select * from infobz where info.infid=infobz.infid )

說明：--

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

說明：--

SQL:

select * from studentinfo where not exists(select * from student where studentinfo.id=student.id) and 系名稱='"&strdepartmentname&"' and 專業名稱='"&strprofessionname&"' order by 性别,生源地,聯考總成績

說明：

從資料庫中去一年的各機關電話費統計(電話費定額賀電化肥清單兩個表來源）

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')

說明：四表聯查問題：

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 .....

說明：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)

====================================

SQL語句技巧

1、一個SQL語句的問題:行列轉換

select * from v_temp

上面的視圖結果如下:

user_name role_name

-------------------------

系統管理者管理者

feng 管理者

feng 一般使用者

test 一般使用者

想把結果變成這樣:

user_name role_name

---------------------------

系統管理者管理者

feng 管理者,一般使用者

test 一般使用者

===================

create table a_test(name varchar(20),role2 varchar(20))

insert into a_test values('李','管理員')

insert into a_test values('張','管理員')

insert into a_test values('張','一般用戶')

insert into a_test values('常','一般用戶')

create function join_str(@content varchar(100))

returns varchar(2000)

begin

declare @str varchar(2000)

set @str=''

select @[email protected]+','+rtrim(role2) from a_test where [name][email protected]

select @str=right(@str,len(@str)-1)

return @str

end

--調用：

select [name],dbo.join_str([name]) role2 from a_test group by [name]

--select distinct name,dbo.uf_test(name) from a_test

2、求助！快速比較結構相同的兩表

結構相同的兩表，一表有記錄3萬條左右，一表有記錄2萬條左右，我怎樣快速查找兩表的不同記錄？

============================

給你一個測試方法，從northwind中的orders表取資料。

select * into n1 from orders

select * into n2 from orders

select * from n1

select * from n2

--添加主鍵，然後修改n1中若幹字段的若幹條

alter table n1 add constraint pk_n1_id primary key (OrderID)

alter table n2 add constraint pk_n2_id primary key (OrderID)

select OrderID from (select * from n1

union

select * from n2) a group by OrderID having count(*) > 1

應該可以，而且将不同的記錄的ID顯示出來。

下面的适用于雙方記錄一樣的情況，

select * from n1 where orderid in

(

select OrderID from (select * from n1

union

select * from n2) a group by OrderID having count(*) > 1

)

至于雙方互不存在的記錄是比較好處理的

--删除n1,n2中若幹條記錄

delete from n1 where orderID in ('10728','10730')

delete from n2 where orderID in ('11000','11001')

--*************************************************************

-- 雙方都有該記錄卻不完全相同

select * from n1 where orderid in

(

select OrderID from (select * from n1

union

select * from n2) a group by OrderID having count(*) > 1

)

union

--n2中存在但在n1中不存的在10728,10730

select * from n1 where OrderID not in (select OrderID from n2)

union

--n1中存在但在n2中不存的在11000,11001

select * from n2 where OrderID not in (select OrderID from n1)

四種方法取表裡n到m條紀錄：

select top m * into 臨時表(或表變量) from tablename order by columnname -- 将top m筆插入

set rowcount n

select * from 表變量 order by columnname desc

select top n * from

(select top m * from tablename order by columnname) a

order by columnname desc

3.如果tablename裡沒有其他identity列，那麼：

select identity(int) id0,* into #temp from tablename

取n到m條的語句為：

select * from #temp where id0 >=n and id0 <= m

如果你在執行select identity(int) id0,* into #temp from tablename這條語句的時候報錯,那是因為你的DB中間的select into/bulkcopy屬性沒有打開要先執行：

exec sp_dboption 你的DB名字,'select into/bulkcopy',true

4.如果表裡有identity屬性，那麼簡單：

select * from tablename where identitycol between n and m

5.如何删除一個表中重複的記錄？

create table a_dist(id int,name varchar(20))

insert into a_dist values(1,'abc')

exec up_distinct 'a_dist','id'

select * from a_dist

create procedure up_distinct(@t_name varchar(30),@f_key varchar(30))

--f_key表示是分組字段﹐即主鍵字段

begin

declare @max integer,@id varchar(30) ,@sql varchar(7999) ,@type integer

select @sql = 'declare cur_rows cursor for select '[email protected]_key+' ,count(*) from ' [email protected]_name +' group by ' [email protected]_key +' having count(*) > 1'

exec(@sql)

open cur_rows

fetch cur_rows into @id,@max

while @@fetch_status=0

begin

select @max = @max -1

set rowcount @max

select @type = xtype from syscolumns where id=object_id(@t_name) and [email protected]_key

if @type=56

select @sql = 'delete from '[email protected]_name+' where ' + @f_key+' = '+ @id

if @type=167

select @sql = 'delete from '[email protected]_name+' where ' + @f_key+' = '+''''+ @id +''''

exec(@sql)

fetch cur_rows into @id,@max

end

close cur_rows

deallocate cur_rows

set rowcount 0

end

select * from systypes

select * from syscolumns where id = object_id('a_dist')

6.查詢資料的最大排序問題（隻能用一條語句寫）

CREATE TABLE hard (qu char (11) ,co char (11) ,je numeric(3, 0))

insert into hard values ('A','1',3)

insert into hard values ('A','2',4)

insert into hard values ('A','4',2)

insert into hard values ('A','6',9)

insert into hard values ('B','1',4)

insert into hard values ('B','2',5)

insert into hard values ('B','3',6)

insert into hard values ('C','3',4)

insert into hard values ('C','6',7)

insert into hard values ('C','2',3)

要求查詢出來的結果如下：

qu co je

----------- ----------- -----

A 6 9

A 2 4

B 3 6

B 2 5

C 6 7

C 3 4

就是要按qu分組，每組中取je最大的前2位！！

而且隻能用一句sql語句！！！

select * from hard a where je in (select top 2 je from hard b where a.qu=b.qu order by je)

7.求删除重複記錄的sql語句？

怎樣把具有相同字段的紀錄删除，隻留下一條。

例如，表test裡有id,name字段

如果有name相同的記錄隻留下一條，其餘的删除。

name的内容不定，相同的記錄數不定。

有沒有這樣的sql語句？

==============================

A:一個完整的解決方案：

将重複的記錄記入temp1表:

select [标志字段id],count(*) into temp1 from [表名]

group by [标志字段id]

having count(*)>1

2、将不重複的記錄記入temp1表:

insert temp1

select [标志字段id],count(*) from [表名]

group by [标志字段id]

having count(*)=1

3、作一個包含所有不重複記錄的表：

select * into temp2 from [表名]

where 标志字段id in(select 标志字段id from temp1)

4、删除重複表:

delete [表名]

5、恢複表：

insert [表名]

select * from temp2

6、删除臨時表:

drop table temp1

drop table temp2

================================

create table a_dist(id int,name varchar(20))

insert into a_dist values(1,'abc')

exec up_distinct 'a_dist','id'

select * from a_dist

create procedure up_distinct(@t_name varchar(30),@f_key varchar(30))

--f_key表示是分組字段﹐即主鍵字段

begin

declare @max integer,@id varchar(30) ,@sql varchar(7999) ,@type integer

select @sql = 'declare cur_rows cursor for select '[email protected]_key+' ,count(*) from ' [email protected]_name +' group by ' [email protected]_key +' having count(*) > 1'

exec(@sql)

open cur_rows

fetch cur_rows into @id,@max

while @@fetch_status=0

begin

select @max = @max -1

set rowcount @max

select @type = xtype from syscolumns where id=object_id(@t_name) and [email protected]_key

if @type=56

select @sql = 'delete from '[email protected]_name+' where ' + @f_key+' = '+ @id

if @type=167

select @sql = 'delete from '[email protected]_name+' where ' + @f_key+' = '+''''+ @id +''''

exec(@sql)

fetch cur_rows into @id,@max

end

close cur_rows

deallocate cur_rows

set rowcount 0

end

select * from systypes

select * from syscolumns where id = object_id('a_dist')

精妙SQL語句（轉帖）

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