Re: Selecting data from one table that is not in another

[Brent Baisley]

MySQL would eventually finish that query, but it's a big. You are 
joining every record in one database with every record in another, 
except where the id's match. You would probably end up with a result 
set of 499,000 records, assuming there is a one to one match with ids.

What you want to do is a left join and check for no match, like this:
SELECT t1.*,t2.model_id FROM data1 as t1
LEFT JOIN data2 as t2 ON t1.model_id=t2.model_id
WHERE t2.model_id IS NULL
You should be able to find lots of examples of this in the archives. 
This comes up a lot.

On Tuesday, November 4, 2003, at 02:31 PM, Agrin, Nathan wrote:

I'm looking for a way to select data from one table that is not found 
in
another.  I am sorting on a column called 'model_id'.  Basically I want
something like this to work:

"SELECT t1.*, t2.model_id FROM data1 as t1, data2 as t2 WHERE
t1.model_id != t2.model_id"
t1 has about 1000 entries and t2 has around 500.  Unfortunately when I
run this SQL query mySQL seems to hang up and never produces any data.
I'm running this through PHP and trying to display the information
returned on a webpage.  If you need any other info in order to help me,
let me know.
Thanks in advance,
-Nate
--
Brent Baisley
Systems Architect
Landover Associates, Inc.
Search & Advisory Services for Advanced Technology Environments
p: 212.759.6400/800.759.0577
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