Add identity increment property to existing tables at once - sql

Question

I have multiple tables in database all table has id column which is primary key.
I want a script by which i can add identity property to all tables at once rather than I go and change one by one.

Answer 1

You can't alter the existing columns for identity.
You have 2 options:
Create a new table with identity & drop the existing table
Create a new column with identity & drop the existing column
But take spl care when these columns have any constraints / relations.
For already craeted table Names
Drop table Names
Create table Names
(
ID int,
Name varchar(50)
)
Insert Into Names Values(1,'SQL Server')
Insert Into Names Values(2,'ASP.NET')
Insert Into Names Values(4,'C#')
In this Approach you can retain the existing data values on the newly
created identity column
CREATE TABLE dbo.Tmp_Names
(
Id int NOT NULL IDENTITY (1, 1),
Name varchar(50) NULL
) ON [PRIMARY]
go
SET IDENTITY_INSERT dbo.Tmp_Names ON
go
IF EXISTS(SELECT * FROM dbo.Names)
INSERT INTO dbo.Tmp_Names (Id, Name)
SELECT Id, Name FROM dbo.Names TABLOCKX
go
SET IDENTITY_INSERT dbo.Tmp_Names OFF
go
DROP TABLE dbo.Names
go
Exec sp_rename 'Tmp_Names', 'Names'
In this approach you can’t retain the existing data values on the
newly created identity column;
The identity column will hold the sequence of number
Alter Table Names Add Id_new Int Identity(1,1)
Go
Alter Table Names Drop Column ID
Go
Exec sp_rename 'Names.Id_new', 'ID','Column'
Source 1
What you can do is write a quick query to generate the SQL for you
like so:
USE INFORMATION_SCHEMA;
SELECT
CONCAT("ALTER TABLE `", TABLE_SCHEMA,"`.`", TABLE_NAME, "` CONVERT TO CHARACTER SET UTF8;")
AS MySQLCMD FROM TABLES
WHERE TABLE_SCHEMA = "your_schema_goes_here";
Then you can run the output from this to do what you need.
Source 2
EDIT
You could check Altering Multiple Tables at once