说明:删除主键: Alter table tabname drop primary key(col)
创建索引
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create [unique] index idxname on tabname(col….)
删除索引:
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drop index idxname
注:索引是不可更改的,想更改必须删除重新建。
创建视图
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createview viewname asselect statement
删除视图
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dropview viewname
几个简单的基本的 SQL 语句
语句
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选择:select*from table1 where 范围 插入:insert into table1(field1,field2) values(value1,value2) 删除:deletefrom table1 where 范围 更新:update table1 set field1=value1 where 范围 查找:select*from table1 where field1 like ’%value1%’ ---like的语法很精妙,查资料! 排序:select*from table1 orderby field1,field2 [desc] 总数:select count as totalcount from table1 求和:selectsum(field1) as sumvalue from table1 平均:selectavg(field1) as avgvalue from table1 最大:selectmax(field1) as maxvalue from table1 最小:selectmin(field1) as minvalue from table1
几个高级查询运算词
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。
法一:select * into b from a where 1<>1(仅用于SQlServer)
法二:select top 0 * into b from a
拷贝表(拷贝数据,源表名:a 目标表名:b)
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insert into b(a, b, c) select d,e,f from b
跨数据库之间表的拷贝(具体数据使用绝对路径)
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insert into b(a, b, c) select d,e,f from b in ‘具体数据库’ where 条件
例子:..from b in ‘“&Server.MapPath(“.”)&”\data.mdb” &”‘ where..
子查询(表名1:a 表名2:b)
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select a,b,c from a where a IN (select d from b )
或者
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select a,b,c from a where a IN (1,2,3)
显示文章、提交人和最后回复时间
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select a.title,a.username,b.adddate fromtable a,(selectmax(adddate) adddate fromtablewhere table.title=a.title) b
外连接查询(表名1:a 表名2:b)
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select a.a, a.b, a.c, b.c, b.d, b.f from a LEFTOUTJOIN b ON a.a = b.c
第二部分
在线视图查询(表名1:a )
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`select*from (SELECT a,b,c FROM a) T where t.a >1
between的用法,between限制查询数据范围时包括了边界值,not between不包括
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select*from table1 wheretimebetween time1 and time2 select a,b,c, from table1 where a notbetween 数值1and 数值2
in 的使用方法
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select*from table1 where a [not] in (‘值1’,’值2’,’值4’,’值6’)
两张关联表,删除主表中已经在副表中没有的信息
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deletefrom table1 wherenotexists ( select*from table2 where table1.field1=table2.field1 )
四表联查问题
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select*from a leftinnerjoin b on a.a=b.b rightinnerjoin c on a.a=c.c innerjoin d on a.a=d.d where .....
日程安排提前五分钟提醒
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SQL: select*from 日程安排 where datediff('minute',f开始时间,getdate())>5
一条sql 语句搞定数据库分页
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select top 10 b.*from (select top 20 主键字段,排序字段 from 表名 orderby 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 orderby a.排序字段
具体实现:
关于数据库分页
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declare@startint,@endint @sql nvarchar(600) set@sql=’select top’+str(@end-@start+1)+’+from T where rid notin(select top’+str(@str-1)+’Rid from T where Rid>-1)’ exec sp_executesql @sql
(select a from tableA ) except (select a from tableB) except (select a from tableC)
随机取出10条数据
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select top 10*from tablename orderby newid()
随机选择记录
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select newid()
删除重复记录
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deletefrom tablename where id notin (selectmax(id) from tablename groupby col1,col2,...) selectdistinct*into temp from tablename deletefrom tablename insert into tablename select*from temp
select type,sum(case vender when'A'then pcs else0end),sum(case vender when'C'then pcs else0end),sum(case vender when'B'then pcs else0end) FROM tablename groupby type
显示结果:
type vender pcs 电脑 A 1 电脑 A 1 光盘 B 2 光盘 A 2 手机 B 3 手机 C 3
初始化表table1
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TRUNCATETABLE table1
选择从10到15的记录
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select top 5*from (select top 15*fromtableorderby id asc) table_别名 orderby id desc
技巧
1=1,1=2的使用,在SQL语句组合时用的较多
“where 1=1” 是表示选择全部 “where 1=2”全部不选,如:
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if @strWhere!='' begin set@strSQL='select count(*) as Total from ['+@tblName+'] where '+@strWhere end else begin set@strSQL='select count(*) as Total from ['+@tblName+']' end
我们可以直接写成
错误!未找到目录项。
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set@strSQL='select count(*) as Total from ['+@tblName+'] where 1=1 安定 '+@strWhere2、收缩数据库
第五部分
重建索引
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DBCC REINDEX DBCC INDEXDEFRAG
收缩数据和日志
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DBCC SHRINKDB DBCC SHRINKFILE
压缩数据库
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dbcc shrinkdatabase(dbname)
转移数据库 给新用户以已存在用户权限
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exec sp_change_users_login 'update_one','newname','oldname' go
检查备份集
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RESTORE VERIFYONLY from disk='E:\dvbbs.bak'
修复数据库
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ALTER DATABASE [dvbbs] SET SINGLE_USER GO DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK GO ALTER DATABASE [dvbbs] SET MULTI_USER GO
SET NOCOUNT ON DECLARE@LogicalFileName sysname, @MaxMinutesINT, @NewSizeINT
USE tablename -- 要操作的数据库名 SELECT@LogicalFileName='tablename_log', -- 日志文件名 @MaxMinutes=10, -- Limit on time allowed to wrap log. @NewSize=1-- 你想设定的日志文件的大小(M) Setup / initialize DECLARE@OriginalSizeint SELECT@OriginalSize= size FROM sysfiles WHERE name =@LogicalFileName SELECT'Original Size of '+ db_name() +' LOG is '+ CONVERT(VARCHAR(30),@OriginalSize) +' 8K pages or '+ CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) +'MB' FROM sysfiles WHERE name =@LogicalFileName CREATE TABLE DummyTrans (DummyColumn char (8000) not null)
DECLARE@CounterINT, @StartTime DATETIME, @TruncLogVARCHAR(255) SELECT@StartTime= GETDATE(), @TruncLog='BACKUP LOG '+ db_name() +' WITH TRUNCATE_ONLY' DBCC SHRINKFILE (@LogicalFileName, @NewSize) EXEC (@TruncLog) -- Wrap the log if necessary. WHILE @MaxMinutes> DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired AND@OriginalSize= (SELECT size FROM sysfiles WHERE name =@LogicalFileName) AND (@OriginalSize*8/1024) >@NewSize BEGIN-- Outer loop. SELECT@Counter=0 WHILE ((@Counter<@OriginalSize/16) AND (@Counter<50000)) BEGIN-- update INSERT DummyTrans VALUES ('Fill Log') DELETE DummyTrans SELECT@Counter=@Counter+1 END EXEC (@TruncLog) END SELECT'Final Size of '+ db_name() +' LOG is '+ CONVERT(VARCHAR(30),size) +' 8K pages or '+ CONVERT(VARCHAR(30),(size*8/1024)) +'MB' FROM sysfiles WHERE name =@LogicalFileName DROPTABLE DummyTrans SET NOCOUNT OFF
CREATEPROCEDURE dbo.User_ChangeObjectOwnerBatch @OldOwneras NVARCHAR(128), @NewOwneras NVARCHAR(128) AS DECLARE@Nameas NVARCHAR(128) DECLARE@Owneras NVARCHAR(128) DECLARE@OwnerNameas NVARCHAR(128) DECLARE curObject CURSORFOR select'Name'= name, 'Owner'= user_name(uid) from sysobjects where user_name(uid)=@OldOwner orderby name OPEN curObject FETCH NEXT FROM curObject INTO@Name, @Owner WHILE(@@FETCH_STATUS=0) BEGIN if @Owner=@OldOwner begin set@OwnerName=@OldOwner+'.'+ rtrim(@Name) exec sp_changeobjectowner @OwnerName, @NewOwner end -- select @name,@NewOwner,@OldOwner FETCH NEXT FROM curObject INTO@Name, @Owner END close curObject deallocate curObject GO
SQL SERVER中直接循环写入数据
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declare@iint set@i=1 while @i<30 begin insert into test (userid) values(@i) set@i=@i+1 end
案例:有如下表,要求就裱中所有沒有及格的成績,在每次增長0.1的基礎上,使他們剛好及格:
Name
score
Zhangshan
80
Lishi
59
Wangwu
50
Songquan
69
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while((selectmin(score) from tb_table)<60) begin update tb_table set score =score*1.01 where score<60 if (selectmin(score) from tb_table)>60 break else continue end
declare@listvarchar(1000), @sql nvarchar(1000) select@list=@list+','+b.name from sysobjects a,syscolumns b where a.id=b.id and a.name='表A' set@sql='select '+right(@list,len(@list)-1)+' from 表A' exec (@sql)
查看硬盘分区:
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EXEC master..xp_fixeddrives
比较A,B表是否相等:
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if (select checksum_agg(binary_checksum(*)) from A) = (select checksum_agg(binary_checksum(*)) from B) print '相等' else print '不相等'
杀掉所有的事件探察器进程:
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DECLARE hcforeach CURSORGLOBALFORSELECT'kill '+RTRIM(spid) FROM master.dbo.sysprocesses WHERE program_name IN('SQL profiler',N'SQL 事件探查器') EXEC sp_msforeach_worker '?'
记录搜索:
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开头到N条记录 Select Top N * From 表 ------------------------------- N到M条记录(要有主索引ID) Select Top M-N * From 表 Where ID in (Select Top M ID From 表) Order by ID Desc ---------------------------------- N到结尾记录
select top 10 recid from A where recid notin(select top 30 recid from A)
分析:如果这样写会产生某些问题,如果recid在表中存在逻辑索引。 select top 10 recid from A where……是从索引中查找,而后面的select top 30 recid from A则在数据表中查找,这样由于索引中的顺序有可能和数据表中的不一致,这样就导致查询到的不是本来的欲得到的数据。
解决方案
用order by select top 30 recid from A order by ricid 如果该字段不是自增长,就会出现问题
在那个子查询中也加条件:select top 30 recid from A where recid>-1
例2:查询表中的最后以条记录,并不知道这个表共有多少数据,以及表结构。
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set@s='select top 1 * from T where pid not in (select top '+ str(@count-1) +' pid from T)' print @sexec sp_executesql @s
获取当前数据库中的所有用户表
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select Name from sysobjects where xtype='u'and status>=0
获取某一个表的所有字段
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select name from syscolumns where id=object_id('表名') select name from syscolumns where id in (select id from sysobjects where type ='u'and name ='表名')
两种方式的效果相同
查看与某一个表相关的视图、存储过程、函数
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select a.*from sysobjects a, syscomments b where a.id = b.id and b.text like'%表名%'
查看当前数据库中所有存储过程
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select name as 存储过程名称 from sysobjects where xtype='P'
查询用户创建的所有数据库
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select * from master..sysdatabases D where sid not in(select sid from master..syslogins where name='sa')
或者
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select dbid, name AS DB_NAME from master..sysdatabases where sid <>0x01
查询某一个表的字段和数据类型
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select column_name,data_type from information_schema.columns where table_name ='表名'
create proc p_process as ```` - 更新修改过的数据 ```sql update b set name=i.name,telphone=i.telphone from srv2.库名.dbo.author b,author i where b.id=i.id and (b.name <> i.name or b.telphone <> i.telphone)
插入新增的数据
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insert srv2.库名.dbo.author(id,name,telphone) select id,name,telphone from author i wherenotexists( select*from srv2.库名.dbo.author where id=i.id)
删除已经删除的数据(如果需要的话)
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delete b from srv2.库名.dbo.author b wherenotexists( select*from author where id=b.id) go