Alter column, add default constraint

I have a table and one of the columns is "Date" of type datetime. We decided to add a default constraint to that column

Alter table TableName
alter column dbo.TableName.Date default getutcdate() 

but this gives me error:

Incorrect syntax near '.'

Does anyone see anything obviously wrong here, which I am missing (other than having a better name for the column)

---

Try this

alter table TableName 
 add constraint df_ConstraintNAme 
 default getutcdate() for [Date]

example

create table bla (id int)

alter table bla add constraint dt_bla default 1 for id



insert bla default values

select * from bla

also make sure you name the default constraint..it will be a pain in the neck to drop it later because it will have one of those crazy system generated names...see also How To Name Default Constraints And How To Drop Default Constraint Without A Name In SQL Server

---

您可以将保留字包装在方括号中以避免以下类型的错误：

dbo.TableName.[Date]

---

I use the stored procedure below to update the defaults on a column.

It automatically removes any prior defaults on the column, before adding the new default.

Examples of usage:

-- 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''';

Stored procedure:

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

Errors this stored procedure eliminates

If you attempt to add a default to a column when one already exists, you will get the following error (something you will never see if using this stored proc):

-- 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.

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