我需要将表的主键更改为标识列,而且表中已经有了许多行。
我有一个脚本来清理ID以确保它们从1开始连续,测试数据库上运行良好。
如何使用SQL命令更改该列以具有标识属性?
我需要将表的主键更改为标识列,而且表中已经有了许多行。
我有一个脚本来清理ID以确保它们从1开始连续,测试数据库上运行良好。
如何使用SQL命令更改该列以具有标识属性?
按照设计,没有简单的方法来为现有列打开或关闭标识属性。唯一的清洁方法是创建一个新列并使其成为标识列,或创建一个新表并迁移数据。
如果我们使用SQL Server Management Studio在列“id”上去掉标识值,将会创建一个新临时表,将数据移到临时表中,删除旧表并重命名新表。
使用管理工具对更改进行操作,然后在设计器中右键单击并选择“生成更改脚本”。
您将看到这就是SQL Server在后台执行的操作。
如果原帖作者实际上想要将现有列设置为表的PRIMARY KEY
,并且实际上不需要该列成为IDENTITY
列(两个不同的事情),那么可以通过t-SQL完成:
ALTER TABLE [YourTableName]
ADD CONSTRAINT [ColumnToSetAsPrimaryKey] PRIMARY KEY ([ColumnToSetAsPrimaryKey])
PRIMARY KEY
选项后面的列名括号。表格不会被删除,表格内的数据和依赖关系保持不变。
修改列的标识属性:
就是这样,对我很有用。
我不相信你可以使用T-SQL修改现有列为标识列。但是,你可以通过Enterprise Manager设计视图来实现。
或者,你可以创建一个新的行作为标识列,删除旧列,然后重命名新列。
ALTER TABLE FooTable
ADD BarColumn INT IDENTITY(1, 1)
NOT NULL
PRIMARY KEY CLUSTERED
--first drop column and add with identity
ALTER TABLE dbo.tblProductPriceList drop column ID
ALTER TABLE dbo.tblProductPriceList add ID INT IDENTITY(1,1)
--then add primary key to that column (exist option you can ignore)
IF NOT EXISTS (SELECT * FROM sys.key_constraints WHERE object_id = OBJECT_ID(N'[dbo].[PK_tblProductPriceList]') AND parent_object_id = OBJECT_ID(N'[dbo].[tblProductPriceList]'))
ALTER TABLE [tblProductPriceList] ADD PRIMARY KEY (id)
GO
生成一个脚本,用于所有具有主键= bigint且未设置标识的表;这将返回每个表的生成脚本列表;
SET NOCOUNT ON;
declare @sql table(s varchar(max), id int identity)
DECLARE @table_name nvarchar(max),
@table_schema nvarchar(max);
DECLARE vendor_cursor CURSOR FOR
SELECT
t.name, s.name
FROM sys.schemas AS s
INNER JOIN sys.tables AS t
ON s.[schema_id] = t.[schema_id]
WHERE EXISTS (
SELECT
[c].[name]
from sys.columns [c]
join sys.types [y] on [y].system_type_id = [c].system_type_id
where [c].[object_id] = [t].[object_id] and [y].name = 'bigint' and [c].[column_id] = 1
) and NOT EXISTS
(
SELECT 1 FROM sys.identity_columns
WHERE [object_id] = t.[object_id]
) and exists (
select 1 from sys.indexes as [i]
inner join sys.index_columns as [ic] ON i.OBJECT_ID = ic.OBJECT_ID AND i.index_id = ic.index_id
where object_name([ic].[object_id]) = [t].[name]
)
OPEN vendor_cursor
FETCH NEXT FROM vendor_cursor
INTO @table_name, @table_schema
WHILE @@FETCH_STATUS = 0
BEGIN
DELETE FROM @sql
declare @pkname varchar(100),
@pkcol nvarchar(100)
SELECT top 1
@pkname = i.name,
@pkcol = COL_NAME(ic.OBJECT_ID,ic.column_id)
FROM sys.indexes AS [i]
INNER JOIN sys.index_columns AS [ic] ON i.OBJECT_ID = ic.OBJECT_ID AND i.index_id = ic.index_id
WHERE i.is_primary_key = 1 and OBJECT_NAME(ic.OBJECT_ID) = @table_name
declare @q nvarchar(max) = 'SELECT '+@pkcol+' FROM ['+@table_schema+'].['+@table_name+'] ORDER BY '+@pkcol+' DESC'
DECLARE @ident_seed nvarchar(max) -- Change this to the datatype that you are after
SET @q = REPLACE(@q, 'SELECT', 'SELECT TOP 1 @output = ')
EXEC sp_executeSql @q, N'@output bigint OUTPUT', @ident_seed OUTPUT
insert into @sql(s) values ('BEGIN TRANSACTION')
insert into @sql(s) values ('BEGIN TRY')
-- create statement
insert into @sql(s) values ('create table ['+@table_schema+'].[' + @table_name + '_Temp] (')
-- column list
insert into @sql(s)
select
' ['+[c].[name]+'] ' +
y.name +
(case when [y].[name] like '%varchar' then
coalesce('('+(case when ([c].[max_length] < 0 or [c].[max_length] >= 1024) then 'max' else cast([c].max_length as varchar) end)+')','')
else '' end)
+ ' ' +
case when [c].name = @pkcol then 'IDENTITY(' +COALESCE(@ident_seed, '1')+',1)' else '' end + ' ' +
( case when c.is_nullable = 0 then 'NOT ' else '' end ) + 'NULL ' +
coalesce('DEFAULT ('+(
REPLACE(
REPLACE(
LTrim(
RTrim(
REPLACE(
REPLACE(
REPLACE(
REPLACE(
LTrim(
RTrim(
REPLACE(
REPLACE(
object_definition([c].default_object_id)
,' ','~')
,')',' ')
)
)
,' ','*')
,'~',' ')
,' ','~')
,'(',' ')
)
)
,' ','*')
,'~',' ')
) +
case when object_definition([c].default_object_id) like '%get%date%' then '()' else '' end
+
')','') + ','
from sys.columns c
JOIN sys.types y ON y.system_type_id = c.system_type_id
where OBJECT_NAME(c.[object_id]) = @table_name and [y].name != 'sysname'
order by [c].column_id
update @sql set s=left(s,len(s)-1) where id=@@identity
-- closing bracket
insert into @sql(s) values( ')' )
insert into @sql(s) values( 'SET IDENTITY_INSERT ['+@table_schema+'].['+@table_name+'_Temp] ON')
declare @cols nvarchar(max)
SELECT @cols = STUFF(
(
select ',['+c.name+']'
from sys.columns c
JOIN sys.types y ON y.system_type_id = c.system_type_id
where c.[object_id] = OBJECT_ID(@table_name)
and [y].name != 'sysname'
and [y].name != 'timestamp'
order by [c].column_id
FOR XML PATH ('')
)
, 1, 1, '')
insert into @sql(s) values( 'IF EXISTS(SELECT * FROM ['+@table_schema+'].['+@table_name+'])')
insert into @sql(s) values( 'EXEC(''INSERT INTO ['+@table_schema+'].['+@table_name+'_Temp] ('+@cols+')')
insert into @sql(s) values( 'SELECT '+@cols+' FROM ['+@table_schema+'].['+@table_name+']'')')
insert into @sql(s) values( 'SET IDENTITY_INSERT ['+@table_schema+'].['+@table_name+'_Temp] OFF')
insert into @sql(s) values( 'DROP TABLE ['+@table_schema+'].['+@table_name+']')
insert into @sql(s) values( 'EXECUTE sp_rename N''['+@table_schema+'].['+@table_name+'_Temp]'', N'''+@table_name+''', ''OBJECT''')
if ( @pkname is not null ) begin
insert into @sql(s) values('ALTER TABLE ['+@table_schema+'].['+@table_name+'] ADD CONSTRAINT ['+@pkname+'] PRIMARY KEY CLUSTERED (')
insert into @sql(s)
select ' ['+COLUMN_NAME+'] ASC,' from information_schema.key_column_usage
where constraint_name = @pkname
GROUP BY COLUMN_NAME, ordinal_position
order by ordinal_position
-- remove trailing comma
update @sql set s=left(s,len(s)-1) where id=@@identity
insert into @sql(s) values (' )')
end
insert into @sql(s) values ('--Run your Statements')
insert into @sql(s) values ('COMMIT TRANSACTION')
insert into @sql(s) values ('END TRY')
insert into @sql(s) values ('BEGIN CATCH')
insert into @sql(s) values (' ROLLBACK TRANSACTION')
insert into @sql(s) values (' DECLARE @Msg NVARCHAR(MAX) ')
insert into @sql(s) values (' SELECT @Msg=ERROR_MESSAGE() ')
insert into @sql(s) values (' RAISERROR(''Error Occured: %s'', 20, 101,@msg) WITH LOG')
insert into @sql(s) values ('END CATCH')
declare @fqry nvarchar(max)
-- result!
SELECT @fqry = (select char(10) + s from @sql order by id FOR XML PATH (''))
SELECT @table_name as [Table_Name], @fqry as [Generated_Query]
PRINT 'Table: '+@table_name
EXEC sp_executeSql @fqry
FETCH NEXT FROM vendor_cursor
INTO @table_name, @table_schema
END
CLOSE vendor_cursor;
DEALLOCATE vendor_cursor;
基本上有四个逻辑步骤。
创建一个新的标识列。为这个新列打开插入标识。
将源列(您希望转换为标识的列)中的数据插入到这个新列中。
关闭新列的插入标识。
删除源列并将新列重命名为源列的名称。
可能会有一些更复杂的问题,比如跨多个服务器工作等。
请参考以下文章以了解步骤(使用ssms和T-sql)。这些步骤适用于对T-SQL掌握较少的初学者。