作為一名programmer，積累代碼是很重要的。下面是我從網(wǎng)上搜集得到的一些精彩的SQL代碼，可以作為平常編寫SQL代碼時(shí)做參考之用。

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• 說明：復(fù)制表(只復(fù)制結(jié)構(gòu),源表名：a 新表名：b)
  select * into b from a where 1<>1
• 說明：拷貝表(拷貝數(shù)據(jù),源表名：a 目標(biāo)表名：b)
  insert into b(a, b, c) select d,e,f from b;
• 說明：顯示文章、提交人和最后回復(fù)時(shí)間
  select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b
• 說明：外連接查詢(表名1：a 表名2：b)
  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
  select * from 日程安排 where datediff('minute',f開始時(shí)間,getdate())>5
• 說明：兩張關(guān)聯(lián)表，刪除主表中已經(jīng)在副表中沒有的信息
  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：--
  select * from studentinfo where not exists(select * from student where studentinfo.id=student.id) and 系名稱='"&strdepartmentname&"' and 專業(yè)名稱='"&strprofessionname&"' order by 性別,生源地,高考總成績(jī)
• 從數(shù)據(jù)庫中去一年的各單位電話費(fèi)統(tǒng)計(jì)(電話費(fèi)定額賀電化肥清單兩個(gè)表來源）
  
  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(lián)查問題
  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號(hào)
• 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)
• 一個(gè)SQL語句的問題:行列轉(zhuǎn)換
  select * from v_temp
  上面的視圖結(jié)果如下:
  user_name role_name
  -------------------------
  系統(tǒng)管理員 管理員
  feng 管理員
  feng 一般用戶
  test 一般用戶
  想把結(jié)果變成這樣:
  user_name role_name
  ---------------------------
  系統(tǒng)管理員 管理員
  feng 管理員,一般用戶
  test 一般用戶
  ===================
  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)
  as
  begin
  declare @str varchar(2000)
  set @str=''
  select @str=@str+','+rtrim(role2) from a_test where [name]=@content
  select @str=right(@str,len(@str)-1)
  return @str
  end
  go
  
  --調(diào)用：
  select [name],dbo.join_str([name]) role2 from a_test group by [name]
  
  --select distinct name,dbo.uf_test(name) from a_test
• 快速比較結(jié)構(gòu)相同的兩表
  結(jié)構(gòu)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(gè)測(cè)試方法，從northwind中的orders表取數(shù)據(jù)。
  select * into n1 from orders
  select * into n2 from orders
  
  select * from n1
  select * from n2
  
  --添加主鍵，然后修改n1中若干字段的若干條
  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(yīng)該可以，而且將不同的記錄的ID顯示出來。
  下面的適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
  --刪除n1,n2中若干條記錄
  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)
• 四種方法取表里n到m條紀(jì)錄：
  
  1.
  select top m * into 臨時(shí)表(或表變量) from tablename order by columnname -- 將top m筆插入
  set rowcount n
  select * from 表變量 order by columnname desc
  
  
  2.
  select top n * from (select top m * from tablename order by columnname) a order by columnname desc
  
  
  3.如果tablename里沒有其他identity列，那么：
  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(zhí)行select identity(int) id0,* into #temp from tablename這條語句的時(shí)候報(bào)錯(cuò),那是因?yàn)槟愕腄B中間的select into/bulkcopy屬性沒有打開要先執(zhí)行：
  exec sp_dboption 你的DB名字,'select into/bulkcopy',true
  
  
  4.如果表里有identity屬性，那么簡(jiǎn)單：
  select * from tablename where identitycol between n and m
• 如何刪除一個(gè)表中重復(fù)的記錄？
  create table a_dist(id int,name varchar(20))
  
  insert into a_dist values(1,'abc')
  insert into a_dist values(1,'abc')
  insert into a_dist values(1,'abc')
  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
  as
  begin
  declare @max integer,@id varchar(30) ,@sql varchar(7999) ,@type integer
  select @sql = 'declare cur_rows cursor for select '+@f_key+' ,count(*) from ' +@t_name +' group by ' +@f_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 name=@f_key
  if @type=56
  select @sql = 'delete from '+@t_name+' where ' + @f_key+' = '+ @id
  if @type=167
  select @sql = 'delete from '+@t_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')
• 查詢數(shù)據(jù)的最大排序問題（只能用一條語句寫）
  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(jié)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！！
  而且只能用一句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)
• 求刪除重復(fù)記錄的sql語句？
  怎樣把具有相同字段的紀(jì)錄刪除，只留下一條。
  例如，表test里有id,name字段
  如果有name相同的記錄 只留下一條，其余的刪除。
  name的內(nèi)容不定，相同的記錄數(shù)不定。
  有沒有這樣的sql語句？
  ==============================
  A:一個(gè)完整的解決方案：
  
  將重復(fù)的記錄記入temp1表:
  select [標(biāo)志字段id],count(*) into temp1 from [表名]
  group by [標(biāo)志字段id]
  having count(*)>1
  
  2、將不重復(fù)的記錄記入temp1表:
  insert temp1 select [標(biāo)志字段id],count(*) from [表名] group by [標(biāo)志字段id] having count(*)=1
  
  3、作一個(gè)包含所有不重復(fù)記錄的表：
  select * into temp2 from [表名] where 標(biāo)志字段id in(select 標(biāo)志字段id from temp1)
  
  4、刪除重復(fù)表:
  delete [表名]
  
  5、恢復(fù)表：
  insert [表名] select * from temp2
  
  6、刪除臨時(shí)表:
  drop table temp1
  drop table temp2
  ================================
  B:
  create table a_dist(id int,name varchar(20))
  
  insert into a_dist values(1,'abc')
  insert into a_dist values(1,'abc')
  insert into a_dist values(1,'abc')
  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
  as
  begin
  declare @max integer,@id varchar(30) ,@sql varchar(7999) ,@type integer
  select @sql = 'declare cur_rows cursor for select '+@f_key+' ,count(*) from ' +@t_name +' group by ' +@f_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 name=@f_key
  if @type=56
  select @sql = 'delete from '+@t_name+' where ' + @f_key+' = '+ @id
  if @type=167
  select @sql = 'delete from '+@t_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')
• 行列轉(zhuǎn)換--普通
  
  假設(shè)有張學(xué)生成績(jī)表(CJ)如下
  Name Subject Result
  張三 語文 80
  張三 數(shù)學(xué) 90
  張三 物理 85
  李四 語文 85
  李四 數(shù)學(xué) 92
  李四 物理 82
  
  想變成
  姓名 語文 數(shù)學(xué) 物理
  張三 80 90 85
  李四 85 92 82
  
  declare @sql varchar(4000)
  set @sql = 'select Name'
  select @sql = @sql + ',sum(case Subject when '''+Subject+''' then Result end) ['+Subject+']'
  from (select distinct Subject from CJ) as a
  select @sql = @sql+' from test group by name'
  exec(@sql)
  
  行列轉(zhuǎn)換--合并
  
  有表A,
  id pid
  1 1
  1 2
  1 3
  2 1
  2 2
  3 1
  如何化成表B:
  id pid
  1 1,2,3
  2 1,2
  3 1
  
  創(chuàng)建一個(gè)合并的函數(shù)
  create function fmerg(@id int)
  returns varchar(8000)
  as
  begin
  declare @str varchar(8000)
  set @str=''
  select @str=@str+','+cast(pid as varchar) from 表A where id=@id
  set @str=right(@str,len(@str)-1)
  return(@str)
  End
  go
  
  --調(diào)用自定義函數(shù)得到結(jié)果
  select distinct id,dbo.fmerg(id) from 表A
• 如何取得一個(gè)數(shù)據(jù)表的所有列名
  
  方法如下：先從SYSTEMOBJECT系統(tǒng)表中取得數(shù)據(jù)表的SYSTEMID,然后再SYSCOLUMN表中取得該數(shù)據(jù)表的所有列名。
  SQL語句如下：
  declare @objid int,@objname char(40)
  set @objname = 'tablename'
  select @objid = id from sysobjects where id = object_id(@objname)
  select 'Column_name' = name from syscolumns where id = @objid order by colid
  
  或
  
  SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME ='users'
• 通過SQL語句來更改用戶的密碼
  
  修改別人的,需要sysadmin role
  EXEC sp_password NULL, 'newpassword', 'User'
  
  如果帳號(hào)為SA執(zhí)行EXEC sp_password NULL, 'newpassword', sa
• 怎么判斷出一個(gè)表的哪些字段不允許為空？
  
  select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where IS_NULLABLE='NO' and TABLE_NAME=tablename
• 如何在數(shù)據(jù)庫里找到含有相同字段的表？
  a. 查已知列名的情況
  SELECT b.name as TableName,a.name as columnname
  From syscolumns a INNER JOIN sysobjects b
  ON a.id=b.id
  AND b.type='U'
  AND a.name='你的字段名字'
• 未知列名查所有在不同表出現(xiàn)過的列名
  Select o.name As tablename,s1.name As columnname
  From syscolumns s1, sysobjects o
  Where s1.id = o.id
  And o.type = 'U'
  And Exists (
  Select 1 From syscolumns s2
  Where s1.name = s2.name
  And s1.id <> s2.id
  )
• 查詢第xxx行數(shù)據(jù)
  
  假設(shè)id是主鍵：
  select * from (select top xxx * from yourtable) aa where not exists(select 1 from (select top xxx-1 * from yourtable) bb where aa.id=bb.id)
  
  如果使用游標(biāo)也是可以的
  fetch absolute [number] from [cursor_name]
  行數(shù)為絕對(duì)行數(shù)
• SQL Server日期計(jì)算
  a. 一個(gè)月的第一天
  SELECT DATEADD(mm, DATEDIFF(mm,0,getdate()), 0)
  b. 本周的星期一
  SELECT DATEADD(wk, DATEDIFF(wk,0,getdate()), 0)
  c. 一年的第一天
  SELECT DATEADD(yy, DATEDIFF(yy,0,getdate()), 0)
  d. 季度的第一天
  SELECT DATEADD(qq, DATEDIFF(qq,0,getdate()), 0)
  e. 上個(gè)月的最后一天
  SELECT dateadd(ms,-3,DATEADD(mm, DATEDIFF(mm,0,getdate()), 0))
  f. 去年的最后一天
  SELECT dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate()), 0))
  g. 本月的最后一天
  SELECT dateadd(ms,-3,DATEADD(mm, DATEDIFF(m,0,getdate())+1, 0))
  h. 本月的第一個(gè)星期一
  select DATEADD(wk, DATEDIFF(wk,0,
  dateadd(dd,6-datepart(day,getdate()),getdate())
  ), 0)
  i. 本年的最后一天
  SELECT dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0))。
• 獲取表結(jié)構(gòu)[把 'sysobjects' 替換 成 'tablename' 即可]
  
  SELECT CASE IsNull(I.name, '')
  When '' Then ''
  Else '*'
  End as IsPK,
  Object_Name(A.id) as t_name,
  A.name as c_name,
  IsNull(SubString(M.text, 1, 254), '') as pbc_init,
  T.name as F_DataType,
  CASE IsNull(TYPEPROPERTY(T.name, 'Scale'), '')
  WHEN '' Then Cast(A.prec as varchar)
  ELSE Cast(A.prec as varchar) + ',' + Cast(A.scale as varchar)
  END as F_Scale,
  A.isnullable as F_isNullAble
  FROM Syscolumns as A
  JOIN Systypes as T
  ON (A.xType = T.xUserType AND A.Id = Object_id('sysobjects') )
  LEFT JOIN ( SysIndexes as I
  JOIN Syscolumns as A1
  ON ( I.id = A1.id and A1.id = object_id('sysobjects') and (I.status & 0x800) = 0x800 AND A1.colid <= I.keycnt) )
  ON ( A.id = I.id AND A.name = index_col('sysobjects', I.indid, A1.colid) )
  LEFT JOIN SysComments as M
  ON ( M.id = A.cdefault and ObjectProperty(A.cdefault, 'IsConstraint') = 1 )
  ORDER BY A.Colid ASC
• 提取數(shù)據(jù)庫內(nèi)所有表的字段詳細(xì)說明的SQL語句
  
  SELECT
  (case when a.colorder=1 then d.name else '' end) N'表名',
  a.colorder N'字段序號(hào)',
  a.name N'字段名',
  (case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else ''
  end) N'標(biāo)識(shí)',
  (case when (SELECT count(*)
  FROM sysobjects
  WHERE (name in
  (SELECT name
  FROM sysindexes
  WHERE (id = a.id) AND (indid in
  (SELECT indid
  FROM sysindexkeys
  WHERE (id = a.id) AND (colid in
  (SELECT colid
  FROM syscolumns
  WHERE (id = a.id) AND (name = a.name))))))) AND
  (xtype = 'PK'))>0 then '√' else '' end) N'主鍵',
  b.name N'類型',
  a.length N'占用字節(jié)數(shù)',
  COLUMNPROPERTY(a.id,a.name,'PRECISION') as N'長度',
  isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as N'小數(shù)位數(shù)',
  (case when a.isnullable=1 then '√'else '' end) N'允許空',
  isnull(e.text,'') N'默認(rèn)值',
  isnull(g.[value],'') AS N'字段說明'
  FROM syscolumns a
  left join systypes b
  on a.xtype=b.xusertype
  inner join sysobjects d
  on a.id=d.id and d.xtype='U' and d.name<>'dtproperties'
  left join syscomments e
  on a.cdefault=e.id
  left join sysproperties g
  on a.id=g.id AND a.colid = g.smallid
  order by object_name(a.id),a.colorder
• 快速獲取表test的記錄總數(shù)[對(duì)大容量表非常有效]
  
  快速獲取表test的記錄總數(shù):
  select rows from sysindexes where id = object_id('test') and indid in (0,1)
  
  update 2 set KHXH=(ID+1)\2 2行遞增編號(hào)
  update [23] set id1 = 'No.'+right('00000000'+id,6) where id not like 'No%' //遞增
  update [23] set id1= 'No.'+right('00000000'+replace(id1,'No.',''),6) //補(bǔ)位遞增
  delete from [1] where (id%2)=1
  奇數(shù)
• 替換表名字段
  update [1] set domurl = replace(domurl,'Upload/Imgswf/','Upload/Photo/') where domurl like '%Upload/Imgswf/%'
• 截位
  SELECT LEFT(表名, 5)

另：

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1.把某個(gè)字段重新生氣序列(從1到n):
DECLARE @i int
Set @i = 0
Update Table1 Set @i = @i + 1,Field1 = @i

2.按成績(jī)排名次
Update 成績(jī)表
Set a.名次 = (
Select Count(*) + 1
From 成績(jī)表 b
Where a.總成績(jī) < b.總成績(jī)
)
From 成績(jī)表 a

3.查詢外部數(shù)據(jù)庫
Select a.*
From OpenRowSet('Microsoft.Jet.OLEDB.4.0','c:\test.mdb';'admin';'',Table1) a

4.查詢Excel文件
Select *
From OpenDataSource('Microsoft.Jet.OLEDB.4.0','Data Source="c:\test.xls";User ID=Admin;Password=;Extended properties=Excel 8.0')...Sheet1$

5.在查詢中指定排序規(guī)則
Select * From Table1 Order By Field1 COLLATE Chinese_PRC_BIN
為什么要指定排序規(guī)則呢?參見:
http://www.delphibbs.com/delphibbs/dispq.asp?lid=1633985
例,檢查數(shù)據(jù)庫中的Pub_Users表中是否存在指定的用戶:
Select Count(*) From Pub_Users Where [UserName]='admin' And [PassWord]='aaa' COLLATE Chinese_PRC_BIN
默認(rèn)比較是不區(qū)分大小寫的,如果不加COLLATE Chinese_PRC_BIN,那么密碼aaa與AAA是等效的,這當(dāng)然與實(shí)際不符.注意的是,每個(gè)條件都要指定排序規(guī)則,上例中用戶名就不區(qū)分大小寫.

6.Order By的一個(gè)小技巧
Order By可以指定列序而不用指定列名,在下面的例子里說明它的用處(注意,第三列未指定別名)
Select a.ID,a.Name,(Select Count(*) From TableB b Where a.ID=b.PID) From TableA a Order By 3