Delete MySQL row using where clause

Question

I'm trying to delete duplicate rows according to some fileds. When I'm running the query below:

delete
    from slowmo_vid as sv1, slowmo_vid as sv2
    where sv1.video_id = '2luh6g3ni5ex'
    and sv1.slowmo_end_t<=sv2.slowmo_end_t;

I'm getting the error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'as sv1, slowmo_vid as sv2
where sv1.video_id = '2luh6g3ni5ex'
and sv1.slowmo_end' at line 2

The fields of the tables are : id, video_id internal_uri, slowmo_end_t

if you wan't use multi Tables for the DELETE use the JOIN statement instead of FROM Table1, Table2 — throrin19
– throrin19, Commented Dec 7, 2015 at 9:15

Tim Biegeleisen · Accepted Answer · 2015-12-07 13:13:31Z

5

You seem to be trying to do an ANSI-92 style inner join inside a DELETE statement. But the WHERE clause cannot simultaneously be used to enforce the join and enforce a restriction on a result set. Instead, do the following explicit INNER JOIN to remove the records you want. Notice that it is clear what role the WHERE clause is playing.

Update: If you want to delete all records except for the one containing the max video_id then you can add a nested subquery to the WHERE clause.

DELETE sv1.*
FROM slowmo_vid sv1
INNER JOIN slowmo_vid sv2 ON sv1.slowmo_end_t <= sv2.slowmo_end_t
WHERE sv1.video_id = '2luh6g3ni5ex' AND
    sv1.video_id <> (SELECT x.id
                     FROM (SELECT MAX(t.video_id) AS id 
                             FROM slowmo_vid t) x)

edited Dec 7, 2015 at 13:13

answered Dec 7, 2015 at 9:14

Tim Biegeleisen

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4 Comments

liorko Over a year ago

When I'm running the query its delete all the records that satisfy this condition. Is there a way to delete all of the records except one? I tried to add limit 1 at the end of the query but it didn't help

Tim Biegeleisen Over a year ago

Which record do you wish to keep and what is the logic behind this decision?

liorko Over a year ago

I want to keep the record with max id because it have more updated data

Tim Biegeleisen Over a year ago

I updated the query. Give it a whirl and let us know if you have any problems.

malyy · Accepted Answer · 2015-12-07 09:16:36Z

0

You can specify multiple tables in a DELETE statement to delete rows from one or more tables depending on the particular condition in the WHERE clause. However, you cannot use ORDER BY or LIMIT in a multiple-table DELETE. The table_references clause lists the tables involved in the join. Its syntax is described in Section 12.2.8.1, “JOIN Syntax”.

http://dev.mysql.com/doc/refman/5.6/en/delete.html

The example in the manual is:

DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3
WHERE t1.id=t2.id AND t2.id=t3.id;

answered Dec 7, 2015 at 9:16

malyy

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Comments

Daimos · Accepted Answer · 2015-12-07 09:14:50Z

-2

You cannot use aliases on DELETE statement. You can try with:

DELETE FROM myAlias USING `my_table` AS myAlias

Or try without any aliases

answered Dec 7, 2015 at 9:14

Daimos

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