I have two tables in a SQL Server 2008 environment with the following structure
Table1 - ID - DescriptionID - Description Table2 - ID - Description <
Table1 - ID - DescriptionID - Description Table2 - ID - Description
You can do this through a regular UPDATE with a JOIN
UPDATE
JOIN
UPDATE T1 SET Description = T2.Description FROM Table1 T1 JOIN Table2 T2 ON T2.ID = T1.DescriptionId