Problem solve Get help with specific problems with your technologies, process and projects.

Return non-matching rows from both tables

An Oracle user asks how to return only non-matching rows when joining two tables.

Is there a way of joining two tables to return only non-matching rows? For example, Table1 and Table2 have an identical structure and contain only two columns:

ID   Name
1    John
2    Philip

ID   Name
1    John
3    Andy

The query should return only the following rows:

ID   Name
2    Philip
3    Andy

Currently I am using Unions and NOT IN clause. Is there another way?

Try a FULL OUTER JOIN with IS NULL tests:

select coalesce(Table1.ID,Table2.ID) as ID
     , coalesce(Table1.Name,Table2.Name) as Name
  from Table1 
full outer
  join Table2 
    on Table2.ID = Table1.ID
 where Table1.ID is null
    or Table2.ID is null

Neat, eh?

The only difficulty you might have is that not every database management system supports FULL OUTER JOIN. Many do, because it is part of the SQL standard. If yours doesn't, the UNION is your fallback strategy. My preference is LEFT OUTER JOIN with an IS NULL test as opposed to a NOT EXISTS subquery.

This was last published in January 2008

Dig Deeper on Oracle development languages

Have a question for an expert?

Please add a title for your question

Get answers from a TechTarget expert on whatever's puzzling you.

You will be able to add details on the next page.

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.