Finding Broken Links for Integrity Control

gtk · #1 (**permalink**) 09-26-05, 06:25

I'm trying to find broken links between two tables.
Performing that I can view all the links

Code:

SELECT
	t2.name AS "object",
	t1.name AS "group"
FROM
	t2
	LEFT JOIN t1 ON (t1.t1_id = t2.t1_id)

I get get something like that

Code:

+---------+-----------+
| object  | group     |
+---------+-----------+
| apple   | food      |
| bus     | vehicule  |
| car     | vehicule  |
| chair   | furniture |
| cheese  | food      |
| coat    | cloth     |
| metro   | vehicule  |
| noze    |           |
| table   | furniture |
| water   |           |
| window  |           |
| wine    |           |
+---------+-----------+

But i'm trying to get only the broken ones (objects having no group)

Code:

SELECT
	t2.name AS "object",
	t1.name AS "group"
FROM
	t2
	LEFT JOIN t1 ON (t1.t1_id = t2.t1_id)
WHERE
	t1.name = NULL

I'd like to get

Code:

+---------+-----------+
| object  | group     |
+---------+-----------+
| noze    |           |
| water   |           |
| window  |           |
| wine    |           |
+---------+-----------+

But this one gives me an empty result

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