SQL update from one Table to another based on a ID match

Question

I have a database with account numbers and card numbers. I match these to a file to update any card numbers to the account number, so

Answer 1

try this :

UPDATE
    Table_A
SET
    Table_A.AccountNumber = Table_B.AccountNumber ,
FROM
    dbo.Sales_Import AS Table_A
    INNER JOIN dbo.RetrieveAccountNumber AS Table_B
        ON Table_A.LeadID = Table_B.LeadID 
WHERE
    Table_A.LeadID = Table_B.LeadID