Update and left outer join statements

UPDATE
       t 
SET 
       t.Column1=100
FROM 
       myTableA t 
LEFT JOIN 
       myTableB t2 
ON 
       t2.ID=t.ID

Replace myTableA with your table name and replace Column1 with your column name.

After this simply LEFT JOIN to tableB. t in this case is just an alias for myTableA. t2 is an alias for your joined table, in my example that is myTableB. If you don’t like using t or t2 use any alias name you prefer – it doesn’t matter – I just happen to like using those.