Do you have two tables or just one? If you have two tables (and if the columns are what I am guessing they are), then may be this is what you need:UPDATE a SET
[statusB] = CASE WHEN b.ServerName IS NULL THEN 'No' ELSE 'Yes' END
FROM
TableA a
LEFT JOIN TableB b ON a.Servername = b.ServerName;
If it is all in one table and you are replacing the second column with Yes or No, thenUPDATE TableA SET
TableB = CASE WHEN statusB = TableB THEN 'Yes' ELSE 'No' END;