Checking for table columns before adding them in SQL Server - sql

Question

I need to script out a table modification at work. Rather than do a simple "if exists then drop and create", they want it to check for the new columns I'm adding, and only then alter the table with them if they don't exist.
Could someone help me with the script? Assume a simple table that looks like this currently:
CREATE TABLE myTable (
[ID] [int] NOT NULL,
[FirstName] [varchar] (20) NOT NULL,
[LastName] [varchar] (20) NOT NULL
)
.. I'd like to add an Address field, varchar(50) let's say, but only if it doesn't already exist in the schema.

Answer 1

IF NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'myTable' AND COLUMN_NAME = 'Address')
BEGIN
ALTER TABLE [dbo].[myTable] ADD
[Address] varchar(50) NOT NULL
END

Answer 2

Try this
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[myTable ]') AND type in (N'U'))
BEGIN
DROP TABLE [dbo].[myTable ]
END
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE myTable (
[ID] [int] NOT NULL,
[FirstName] [varchar] (20) NOT NULL,
[LastName] [varchar] (20) NOT NULL,
[Address] [varchar] (50) NOT NULL
)
OR
if not exists(select * from sys.columns
where Name = N'Address' and Object_ID = Object_ID(N'myTable'))
begin
alter table myTable
add Address varchar(50) NOT NULL
end
GO

Answer 3

Try this:
Here using it you can make check for multiple columns and get you table altered...
DECLARE #query VARCHAR(MAX)
IF EXISTS(SELECT * FROM sys.columns
WHERE Name = N'Address' AND OBJECT_ID = OBJECT_ID(N'<TableName>'))
BEGIN
SET
#query = 'ALTER TABLE <TableName> ADD Address varchar(50) GO'
END
--You can give multiple If conditions, example:
--IF EXISTS(SELECT * FROM sys.columns
--WHERE Name = N'<SomeOtherColumn>' AND OBJECT_ID = OBJECT_ID(N'<TableName>'))
--BEGIN
--SET
--#query = #query + 'ALTER TABLE <TableName> ADD <SomeOtherColumn> varchar(50) GO'
--END
EXEC sp_Executesql #query

Answer 4

IF 'col_name'
NOT IN
SELECT Name
FROM table_name.columns
ALTER TABLE table_name
ADD 'col_name' VARCHAR(65) NOT NULL
something like this?
EDIT: my friend believes this is much better
IF NOT EXISTS
(SELECT Name
FROM table_name.columns
Where Name='target_column_name')
ALTER TABLE table_name
ADD 'target_column_name' VARCHAR(65) NOTNULL