how to make existing key to primary key in sql server code example
Example 1: add primary key to existing table sql
alter table Persion add primary key (persionId,Pname,PMID)
Example 2: sql server add primary key to existing table with data
ALTER TABLE Production.TransactionHistoryArchive
ADD CONSTRAINT PK_TransactionHistoryArchive_TransactionID PRIMARY KEY CLUSTERED (TransactionID);