Compare Tables

[tobeyt23]

I have 2 tables one that I update nightly from a data feed and the other that I use within my app. Trying to compare the nightly to the other and update with an additions or changes. How can I accomplish this?

[The Little Guy]

So do you want to have the updated table the exact same as the original table when the process is done?

[tobeyt23]

I want the original to be update with any changes or updates that I pull into the nightly update

[ebmigue]

Assuming the two tables have are exactly the same (i.e., has the same attributes), then the

classical Relational MINUS ought to do the trick.

 

A MINUS B, would return the records of A that are not found in B.

 

However, since that is not supported in SQL, you can simulate it using

WHERE EXISTS, like so:

 

   SELECT * FROM nightly_feed 
   WHERE NOT EXISTS(
        SELECT * FROM
        apps
            WHERE apps.field1 = nightly_feed.field1 AND apps.field2 AND nightly_feed.field2 (AND ..etc..) 
   )

 

In short, use every attribute of the two tables/relvars.

 

 

Hope it helps.