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

Seems you are using MSSQL, then, if I remember correctly, it is done like this:

UPDATE [Sales_Lead].[dbo].[Sales_Import] SET [AccountNumber] = 
RetrieveAccountNumber.AccountNumber 
FROM RetrieveAccountNumber 
WHERE [Sales_Lead].[dbo].[Sales_Import].LeadID = RetrieveAccountNumber.LeadID