我有一个表,其中一列是“日期”类型的日期时间。我们决定默认约束添加到列改变列,添加默认约束
Alter table TableName
alter column dbo.TableName.Date default getutcdate()
,但是这给了我错误:
Incorrect syntax near '.'
有谁看到什么明显的错误在这里,我很想念(除有一个更好的名字列)
我有一个表,其中一列是“日期”类型的日期时间。我们决定默认约束添加到列改变列,添加默认约束
Alter table TableName
alter column dbo.TableName.Date default getutcdate()
,但是这给了我错误:
Incorrect syntax near '.'
有谁看到什么明显的错误在这里,我很想念(除有一个更好的名字列)
试试这个
alter table TableName
add constraint df_ConstraintNAme
default getutcdate() for [Date]
例如
create table bla (id int)
alter table bla add constraint dt_bla default 1 for id
insert bla default values
select * from bla
还要确保你的名字默认constraint..it将在颈部疼痛后放弃它,因为它会那些疯狂的系统的一个所产生的名字......还看到How To Name Default Constraints And How To Drop Default Constraint Without A Name In SQL Server
你可以在方括号包裹保留字,以避免此类错误:
dbo.TableName.[Date]
这似乎是一个非常糟糕的主意,使用列名保留字。 – 2017-09-27 12:44:02
其实你要做的就像下面的例子,这将有助于解决这一问题......
drop table ABC_table
create table ABC_table
(
names varchar(20),
age int
)
ALTER TABLE ABC_table
ADD CONSTRAINT MyConstraintName
DEFAULT 'This is not NULL' FOR names
insert into ABC(age) values(10)
select * from ABC
我使用下面的存储过程更新列上的默认值。
在添加新的默认值之前,它会自动删除列上的所有先前默认值。用法
例子:
-- Update default to be a date.
exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column','getdate()';
-- Update default to be a number.
exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column,'6';
-- Update default to be a string. Note extra quotes, as this is not a function.
exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column','''MyString''';
存储过程:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- Sample function calls:
--exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','ColumnName','getdate()';
--exec [dbol].[AlterDefaultForColumn] '[dbo].[TableName]','Column,'6';
--exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column','''MyString''';
create PROCEDURE [dbo].[ColumnDefaultUpdate]
(
-- Table name, including schema, e.g. '[dbo].[TableName]'
@TABLE_NAME VARCHAR(100),
-- Column name, e.g. 'ColumnName'.
@COLUMN_NAME VARCHAR(100),
-- New default, e.g. '''MyDefault''' or 'getdate()'
-- Note that if you want to set it to a string constant, the contents
-- must be surrounded by extra quotes, e.g. '''MyConstant''' not 'MyConstant'
@NEW_DEFAULT VARCHAR(100)
)
AS
BEGIN
-- Trim angle brackets so things work even if they are included.
set @COLUMN_NAME = REPLACE(@COLUMN_NAME, '[', '')
set @COLUMN_NAME = REPLACE(@COLUMN_NAME, ']', '')
print 'Table name: ' + @TABLE_NAME;
print 'Column name: ' + @COLUMN_NAME;
DECLARE @ObjectName NVARCHAR(100)
SELECT @ObjectName = OBJECT_NAME([default_object_id]) FROM SYS.COLUMNS
WHERE [object_id] = OBJECT_ID(@TABLE_NAME) AND [name] = @COLUMN_NAME;
IF @ObjectName <> ''
begin
print 'Removed default: ' + @ObjectName;
--print('ALTER TABLE ' + @TABLE_NAME + ' DROP CONSTRAINT ' + @ObjectName)
EXEC('ALTER TABLE ' + @TABLE_NAME + ' DROP CONSTRAINT ' + @ObjectName)
end
EXEC('ALTER TABLE ' + @TABLE_NAME + ' ADD DEFAULT (' + @NEW_DEFAULT + ') FOR ' + @COLUMN_NAME)
--print('ALTER TABLE ' + @TABLE_NAME + ' ADD DEFAULT (' + @NEW_DEFAULT + ') FOR ' + @COLUMN_NAME)
print 'Added default of: ' + @NEW_DEFAULT;
END
错误此存储过程消除
如果您尝试将默认添加到列,当一个已经存在,你会得到下面的错误(如果使用这个存储过程你永远不会看到):
-- Using the stored procedure eliminates this error:
Msg 1781, Level 16, State 1, Line 1
Column already has a DEFAULT bound to it.
Msg 1750, Level 16, State 0, Line 1
Could not create constraint. See previous errors.
不要使用类型或关键字作为列名! – JonH 2010-01-19 17:04:40
yup,agree-“有没有人在这里看到任何明显的错误,我错过了(除了有一个更好的名字的列)” – ram 2010-01-19 17:22:18