add a primary key to an existing table 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);