T-SQL Add Column In Specific Order

Aren picture Aren · Jun 3, 2010 · Viewed 26.5k times · Source

Im a bit new to T-SQL, Coming from a MySQL background Im still adapting to the different nuances in the syntax.

Im looking to add a new column AFTER a specific one. I've found out that AFTER is a valid keyword but I don't think it's the right one for the job.

ALTER TABLE [dbo].[InvStockStatus]
ADD [Abbreviation] [nvarchar](32) DEFAULT '' NOT NULL ;

This is my current query, which works well, except it adds the field at the end of the Table, Id prefer to add it after [Name]. What's the syntax im looking for to represent this?

Answer

SQLMenace picture SQLMenace · Jun 3, 2010

You can't do it like that

for example if you have a table like this

create table TestTable(id1 int,id3 int)

and you want to add another column id2 between id1 and id3 then here is what SQL Server does behind the scene if you use the designer

BEGIN TRANSACTION
SET QUOTED_IDENTIFIER ON
SET ARITHABORT ON
SET NUMERIC_ROUNDABORT OFF
SET CONCAT_NULL_YIELDS_NULL ON
SET ANSI_NULLS ON
SET ANSI_PADDING ON
SET ANSI_WARNINGS ON
COMMIT
BEGIN TRANSACTION
GO
CREATE TABLE dbo.Tmp_TestTable
    (
    id1 int NULL,
    id2 int NULL,
    id3 int NULL
    )  ON [PRIMARY]
GO
ALTER TABLE dbo.Tmp_TestTable SET (LOCK_ESCALATION = TABLE)
GO
IF EXISTS(SELECT * FROM dbo.TestTable)
     EXEC('INSERT INTO dbo.Tmp_TestTable (id1, id3)
        SELECT id1, id3 FROM dbo.TestTable WITH (HOLDLOCK TABLOCKX)')
GO
DROP TABLE dbo.TestTable
GO
EXECUTE sp_rename N'dbo.Tmp_TestTable', N'TestTable', 'OBJECT' 
GO
COMMIT

As you can see if you have a lot of data this can be problematic, why does it matter where the column is located? just use

select col1,col2,col3 from table