I have two tables in MySQL
#messages table :
messageid
messagetitle
.
.
#usersmessages table
usersmessageid
messageid
userid
.
.Now if I want to delete from messages table it's ok. But when I delete message by messageid the record still exists on usersmessage and I have to delete from this two tables at once.
I used the following query :
DELETE FROM messages LEFT JOIN usersmessages USING(messageid) WHERE messageid='1' ; Then I test
DELETE FROM messages , usersmessages WHERE messages.messageid = usersmessages.messageid and messageid='1' ; But these two queries are not accomplishing this task .
11 Answers
Can't you just separate them by a semicolon?
Delete from messages where messageid = '1';
Delete from usersmessages where messageid = '1'OR
Just use INNER JOIN as below
DELETE messages , usersmessages FROM messages INNER JOIN usersmessages
WHERE messages.messageid= usersmessages.messageid and messages.messageid = '1'DELETE a.*, b.*
FROM messages a
LEFT JOIN usersmessages b
ON b.messageid = a.messageid
WHERE a.messageid = 1translation: delete from table messages where messageid =1, if table uersmessages has messageid = messageid of table messages, delete that row of uersmessages table.
2You should either create a FOREIGN KEY with ON DELETE CASCADE:
ALTER TABLE usersmessages
ADD CONSTRAINT fk_usermessages_messageid
FOREIGN KEY (messageid)
REFERENCES messages (messageid)
ON DELETE CASCADE, or do it using two queries in a transaction:
START TRANSACTION;;
DELETE
FROM usermessages
WHERE messageid = 1
DELETE
FROM messages
WHERE messageid = 1;
COMMIT;Transaction affects only InnoDB tables, though.
You have two options:
First, do two statements inside a transaction:
BEGIN; DELETE FROM messages WHERE messageid = 1; DELETE FROM usermessages WHERE messageid = 1;
COMMIT;Or, you could have ON DELETE CASCADE set up with a foreign key. This is the better approach.
CREATE TABLE parent ( id INT NOT NULL, PRIMARY KEY (id)
);
CREATE TABLE child ( id INT, parent_id INT, FOREIGN KEY (parent_id) REFERENCES parent(id) ON DELETE CASCADE
);You can read more about ON DELETE CASCADE here.
0no need for JOINS:
DELETE m, um FROM messages m, usersmessages um
WHERE m.messageid = 1
AND m.messageid = um.messageid The OP is just missing the table aliases after the delete
DELETE t1, t2
FROM table1 t1 LEFT JOIN table2 t2 ON t1.id = t2.id
WHERE t1.id = some_idDELETE message.*, usersmessage.* from users, usersmessage WHERE message.messageid=usersmessage.messageid AND message.messageid='1'Try this please
DELETE FROM messages,usersmessages
USING messages
INNER JOIN usermessages on (messages.messageid = usersmessages.messageid)
WHERE messages.messsageid='1'Try this..
DELETE a.*, b.*
FROM table1 as a, table2 as b
WHERE a.id=[Your value here] and b.id=[Your value here]I let id as a sample column.
Glad this helps. :)
1You can also use like this, to delete particular value when both the columns having 2 or many of same column name.
DELETE project , create_test FROM project INNER JOIN create_test
WHERE project.project_name='Trail' and create_test.project_name ='Trail' and project.uid= create_test.uid = '1';there's another way which is not mentioned here (I didn't fully test it's performance yet), you could set array for all tables -> rows you want to delete as below
// set your tables array
$array = ['table1', 'table2', 'table3'];
// loop through each table
for($i = 0; $i < count($array); $i++){ // get each single array $single_array = $array[$i]; // build your query $query = "DELETE FROM $single_array WHERE id = 'id'"; // prepare the query and get the connection $data = con::GetCon()->prepare($query); // execute the action $data->execute();
}then you could redirect the user to the home page.
header('LOCATION:' . $home_page);hope this will help someone :)
Thanks
1
