Bulk Record Update with SQL

Question

I have two tables in a SQL Server 2008 environment with the following structure

Table1 - ID - DescriptionID - Description  Table2 - ID - Description 

Table1.DescriptionID maps to Table2.ID. However, I do not need it any more. I would like to do a bulk update to set the Description property of Table1 to the value associated with it in Table2. In other words I want to do something like this:

UPDATE   [Table1]  SET   [Description]=(SELECT [Description] FROM [Table2] t2 WHERE t2.[ID]=Table1.DescriptionID) 

However, I'm not sure if this is the appropriate approach. Can someone show me how to do this?

Answer 1

Your way is correct, and here is another way you can do it:

update      Table1 set         Description = t2.Description from        Table1 t1 inner join  Table2 t2 on          t1.DescriptionID = t2.ID 

The nested select is the long way of just doing a join.

Answer 2

Your approach is OK

Maybe slightly clearer (to me anyway!)

UPDATE   T1 SET   [Description] = t2.[Description] FROM    Table1 T1    JOIN    [Table2] t2 ON t2.[ID] = t1.DescriptionID 

Both this and your query should run the same performance wise because it is the same query, just laid out differently.