title: Set primary key to existing table
body: <p>I have a table with 15 records. The table does not have any primary key constraint.</p>
  
  <p>Now I want to set a primary key in the existing column. How can I set a column with primary key constraint to the existing table? Can somebody provide the query to alter the column? </p>
  
  <p>It is for SQL server 2008.</p>