• SQL基础


    创建数据库

      创建之前判断该数据库是否存在

      if exists (select * from sysdatabases where name='databaseName')

      drop database databaseName

      go

      Create DATABASE database-name

    删除数据库

      drop database dbname

    备份sql server

      --- 创建 备份数据的 device

      USE master

      EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat'

      --- 开始 备份

      BACKUP DATABASE pubs TO testBack

    创建新表

      create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)

      根据已有的表创建新表:

      A:create table tab_new like tab_old (使用旧表创建新表)

      B:create table tab_new as select col1,col2… from tab_old definition only

    创建序列

      create sequence SIMON_SEQUENCE

      minvalue 1 -- 最小值

      maxvalue 999999999999999999999999999 最大值

      start with 1 开始值

      increment by 1 每次加几

      cache 20;

    删除新表

      drop table tabname

    增加一个列

      Alter table tabname add column col type

      注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。

    添加主键

      Alter table tabname add primary key(col)

      说明:删除主键: Alter table tabname drop primary key(col)

    创建索引

      create [unique] index idxname on tabname(col….)

      删除索引:drop index idxname on tabname

      注:索引是不可更改的,想更改必须删除重新建。

    创建视图

      create view viewname as select statement

      删除视图:drop view viewname

    几个简单的基本的sql语句

      选择:select * from table1 where 范围

      插入:insert into table1(field1,field2) values(value1,value2)

      删除:delete from table1 where 范围

      更新:update table1 set field1=value1 where 范围

      查找:select * from table1 where field1 like ’%value1%’ (所有包含‘value1’这个模式的字符串)---like的语法很精妙,查资料!

      排序:select * from table1 order by field1,field2 [desc]

      总数:select count(*) as totalcount from table1

      求和:select sum(field1) as sumvalue from table1

      平均:select avg(field1) as avgvalue from table1

      最大:select max(field1) as maxvalue from table1

      最小:select min(field1) as minvalue from table1[separator]

    几个高级查询运算词

      A: UNION 运算符

      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。

      B: EXCEPT 运算符

      EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。

      C: INTERSECT 运算符

      INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。

      注:使用运算词的几个查询结果行必须是一致的。

    使用外连接

      A、left outer join:

      左外连接(左连接):结果集既包括连接表的匹配行,也包括左连接表的所有行。

      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

      B:right outer join:

      右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。

      C:full outer join:

      全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。

    提升

    复制表

      (只复制结构,源表名:a 新表名:b) (Access可用)

      法一:select * into b from a where 1<>1

      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) (Access可用)

      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) (Access可用)

      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)

      select a,b,c from a where a IN (select d from b 或者: 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

      select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b

    外连接查询

      (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

    在线视图查询

      (表名1:a

      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

      select * from table1 where time between time1 and time2

      select a,b,c, from table1 where a not between 数值1 and 数值2

    in 的使用方法

      select * from table1 where a [not] in (‘值1’,’值2’,’值4’,’值6’)

    删除主表中已经在副表中没有的信息

      两张关联表delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1

    四表联查问题

      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 .....

    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

    一条sql 语句搞定数据库分页

      select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段

    前10条记录

      select top 10 * form table1 where 范围

    选择排名

      选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.)

      select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b)

    派生结果表

      包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表

      (select a from tableA except (select a from tableB) except (select a from tableC)

    随机取出10条数据

      select top 10 * from tablename order by newid()

    随机选择记录

      select newid()

    删除重复记录

      Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...)

    列出数据库里所有的表名

      select name from sysobjects where type='U'

    列出表里的所有的

      select name from syscolumns where id=object_id('TableName')

    列示排列

      列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。

      select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by 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

      TRUNCATE TABLE table1

    选择从10到15的记录

      select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc

    数据类型转换

      declare @numid int

      declare @id varchar(50)

      set @numid=2005

      set @id=convert(varchar,@numid)

      通过上述语句完成数据类型Int转换成varchar,其他转换类似,可参看convert函数

    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:

      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

      set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere

    收缩数据库

      --重建索引

      DBCC REINDEX

      DBCC INDEXDEFRAG

      --收缩数据和日志

      DBCC SHRINKDB

      DBCC SHRINKFILE

    压缩数据库

      dbcc shrinkdatabase(dbname)

      转移数据库给新用户以已存在用户权限

      exec sp_change_users_login 'update_one','newname','oldname'

      go

    检查备份集

      RESTORE VERIFYONLY from disk='E:\dvbbs.bak'

    修复数据库

      Alter DATABASE [dvbbs] SET SINGLE_USER

      GO

      DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK

      GO

      Alter DATABASE [dvbbs] SET MULTI_USER

      GO

    日志清除

      SET NOCOUNT ON

      DECLARE @LogicalFileName sysname,

      @MaxMinutes INT,

      @NewSize INT

      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 @OriginalSize int

      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 @Counter INT,

      @StartTime DATETIME,

      @TruncLog VARCHAR(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

      Drop TABLE DummyTrans

      SET NOCOUNT OFF

    更改某个表

      exec sp_changeobjectowner 'tablename','dbo'

    存储更改全部表

      Create PROCEDURE dbo.User_ChangeObjectOwnerBatch

      @OldOwner as NVARCHAR(128),

      @NewOwner as NVARCHAR(128)

      AS

      DECLARE @Name as NVARCHAR(128)

      DECLARE @Owner as NVARCHAR(128)

      DECLARE @OwnerName as NVARCHAR(128)

      DECLARE curObject CURSOR FOR

      select 'Name' = name,

      'Owner' = user_name(uid)

      from sysobjects

      where user_name(uid)=@OldOwner

      order by 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

      declare @i int

      set @i=1

      while @i<30

      begin

      insert into test (userid) values(@i)

      set @i=@i+1

      end 

    创建数据库

      创建之前判断该数据库是否存在

      if exists (select * from sysdatabases where name='databaseName')

      drop database databaseName

      go

      Create DATABASE database-name

    删除数据库

      drop database dbname

    备份sql server

      --- 创建 备份数据的 device

      USE master

      EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat'

      --- 开始 备份

      BACKUP DATABASE pubs TO testBack

    创建新表

      create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)

      根据已有的表创建新表:

      A:create table tab_new like tab_old (使用旧表创建新表)

      B:create table tab_new as select col1,col2… from tab_old definition only

    创建序列

      create sequence SIMON_SEQUENCE

      minvalue 1 -- 最小值

      maxvalue 999999999999999999999999999 最大值

      start with 1 开始值

      increment by 1 每次加几

      cache 20;

    删除新表

      drop table tabname

    增加一个列

      Alter table tabname add column col type

      注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。

    添加主键

      Alter table tabname add primary key(col)

      说明:删除主键: Alter table tabname drop primary key(col)

    创建索引

      create [unique] index idxname on tabname(col….)

      删除索引:drop index idxname on tabname

      注:索引是不可更改的,想更改必须删除重新建。

    创建视图

      create view viewname as select statement

      删除视图:drop view viewname

    几个简单的基本的sql语句

      选择:select * from table1 where 范围

      插入:insert into table1(field1,field2) values(value1,value2)

      删除:delete from table1 where 范围

      更新:update table1 set field1=value1 where 范围

      查找:select * from table1 where field1 like ’%value1%’ (所有包含‘value1’这个模式的字符串)---like的语法很精妙,查资料!

      排序:select * from table1 order by field1,field2 [desc]

      总数:select count(*) as totalcount from table1

      求和:select sum(field1) as sumvalue from table1

      平均:select avg(field1) as avgvalue from table1

      最大:select max(field1) as maxvalue from table1

      最小:select min(field1) as minvalue from table1[separator]

    几个高级查询运算词

      A: UNION 运算符

      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。

      B: EXCEPT 运算符

      EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。

      C: INTERSECT 运算符

      INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。

      注:使用运算词的几个查询结果行必须是一致的。

    使用外连接

      A、left outer join:

      左外连接(左连接):结果集既包括连接表的匹配行,也包括左连接表的所有行。

      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

      B:right outer join:

      右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。

      C:full outer join:

      全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。

    提升

    复制表

      (只复制结构,源表名:a 新表名:b) (Access可用)

      法一:select * into b from a where 1<>1

      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) (Access可用)

      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) (Access可用)

      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)

      select a,b,c from a where a IN (select d from b 或者: 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

      select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b

    外连接查询

      (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

    在线视图查询

      (表名1:a

      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

      select * from table1 where time between time1 and time2

      select a,b,c, from table1 where a not between 数值1 and 数值2

    in 的使用方法

      select * from table1 where a [not] in (‘值1’,’值2’,’值4’,’值6’)

    删除主表中已经在副表中没有的信息

      两张关联表delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1

    四表联查问题

      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 .....

    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

    一条sql 语句搞定数据库分页

      select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段

    前10条记录

      select top 10 * form table1 where 范围

    选择排名

      选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.)

      select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b)

    派生结果表

      包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表

      (select a from tableA except (select a from tableB) except (select a from tableC)

    随机取出10条数据

      select top 10 * from tablename order by newid()

    随机选择记录

      select newid()

    删除重复记录

      Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...)

    列出数据库里所有的表名

      select name from sysobjects where type='U'

    列出表里的所有的

      select name from syscolumns where id=object_id('TableName')

    列示排列

      列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。

      select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by 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

      TRUNCATE TABLE table1

    选择从10到15的记录

      select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc

    数据类型转换

      declare @numid int

      declare @id varchar(50)

      set @numid=2005

      set @id=convert(varchar,@numid)

      通过上述语句完成数据类型Int转换成varchar,其他转换类似,可参看convert函数

    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:

      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

      set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere

    收缩数据库

      --重建索引

      DBCC REINDEX

      DBCC INDEXDEFRAG

      --收缩数据和日志

      DBCC SHRINKDB

      DBCC SHRINKFILE

    压缩数据库

      dbcc shrinkdatabase(dbname)

      转移数据库给新用户以已存在用户权限

      exec sp_change_users_login 'update_one','newname','oldname'

      go

    检查备份集

      RESTORE VERIFYONLY from disk='E:\dvbbs.bak'

    修复数据库

      Alter DATABASE [dvbbs] SET SINGLE_USER

      GO

      DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK

      GO

      Alter DATABASE [dvbbs] SET MULTI_USER

      GO

    日志清除

      SET NOCOUNT ON

      DECLARE @LogicalFileName sysname,

      @MaxMinutes INT,

      @NewSize INT

      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 @OriginalSize int

      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 @Counter INT,

      @StartTime DATETIME,

      @TruncLog VARCHAR(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

      Drop TABLE DummyTrans

      SET NOCOUNT OFF

    更改某个表

      exec sp_changeobjectowner 'tablename','dbo'

    存储更改全部表

      Create PROCEDURE dbo.User_ChangeObjectOwnerBatch

      @OldOwner as NVARCHAR(128),

      @NewOwner as NVARCHAR(128)

      AS

      DECLARE @Name as NVARCHAR(128)

      DECLARE @Owner as NVARCHAR(128)

      DECLARE @OwnerName as NVARCHAR(128)

      DECLARE curObject CURSOR FOR

      select 'Name' = name,

      'Owner' = user_name(uid)

      from sysobjects

      where user_name(uid)=@OldOwner

      order by 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

      declare @i int

      set @i=1

      while @i<30

      begin

      insert into test (userid) values(@i)

      set @i=@i+1

      end

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  • 原文地址:https://www.cnblogs.com/tian_z/p/1780483.html
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