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

User · Accepted Answer

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

User · Answer

You can do this through a regular UPDATE with a JOIN      UPDATE T1 SET Description   T2 Description    FROM Table1 T1       JOIN Table2 T2          ON T2 ID   T1 DescriptionId

User · Answer

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

User · Answer

The SQL you posted in your question is one way to do it  Most things in SQL have more than one way to do it   UPDATE    Table1   SET    Description   SELECT  Description  FROM  Table2  t2 WHERE t2  ID  Table1 DescriptionID    If you are planning on running this on a PROD DB  it is best to create a snapshot or mirror of it first and test it out  Verify the data ends up as you expect for a couple records  And if you are satisfied  run it on the real DB

User · Answer

Or you can simply update without using join like this   Update t1 set  t1 Description   t2 Description from  tbl2 t2 tbl1 t1 where t1 ID  t2 ID

[sql] Bulk Record Update with SQL

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