I'm trying to figure out how to write an SQL query that deletes from one table and inserts into another. I have tried writing

DELETE FROM dbo.MojoBeers
WHERE (productID = @productID)
UNION
INSERT INTO dbo.MojoShoppingCart
(productID) VALUES (@productID)

Every time I get a parse error, and I'm not sure why. If you could help me out with this I would be grateful.

    Requires Free Membership to View

    Login

Well, the answer to this is pretty simple. You can't UNION a DELETE and an INSERT. You can only UNION SELECTs. You'll just have to run the DELETE and INSERT as separate statements. Depending on your database system, you might be able to submit both of them in one call to the database if they're separated by a semicolon.

Also, it's more common to do the INSERT first. Typically, you'll want to copy some of the fields from one table to the other. So you would do something like:

insert
  into table2
     ( pkey
     , field1
     , field2
     , fieldN )
select pk
     , col1
     , 'foo2'
     , colN      
  from table1
 where pk = 937

Often, you would run these queries from some scripting language like Coldfusion, ASP, or PHP. It might be wise to check the status code of the INSERT to make sure it was successful before continuing with the DELETE.

delete
  from table1  
 where pk = 937

Yes, there's extra overhead in making two calls to the database instead of one, but it's minimal.

This was first published in June 2005

Join the conversationComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.
    Back to top