title: How to set auto increment to existing primary column field in SQL Server
body: <p>I have created a SQL Server database table but forgot to set auto increment in the primary key column. How can I set the auto increment to the existing primary key field?</p>
  
  <pre><code>CREATE TABLE [dbo].[STUDENT_INFO] 
    ( 
       [ROLLNO]       [INT] IDENTITY(1, 1) NOT NULL, 
       [SCHOOLID]     [INT] NOT NULL, 
       [STUDENTID]    [INT] NOT NULL, 
       [NAME]         [NVARCHAR](50) NOT NULL, 
       [AGE]          [INT] NOT NULL, 
       [GENDER]       [NVARCHAR](10) NOT NULL, 
       [ADDRESS]      [NVARCHAR](500) NULL, 
       [CONTACTNO]    [NVARCHAR](20) NOT NULL, 
       [EMAIL]        [NVARCHAR](50) NULL, 
       [ISACTIVE]     [BIT] NOT NULL, 
       [INSTRUMENTID] [INT] NOT NULL, 
       [GRADEID]      [INT] NOT NULL, 
       [DISCOUNT]     [INT] NOT NULL, 
       [STARTTIME]    [TIME](7) NOT NULL, 
       [DURATION]     [TIME](7) NOT NULL, 
       PRIMARY KEY CLUSTERED ( [STUDENTID] ASC ) WITH (PAD_INDEX = OFF, 
       STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, 
       ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
    ) 
  ON [PRIMARY]
  </code></pre>
  
  <p>I am working with SQL Server Management Studio 2012.</p>