I'm getting this error :
Query Error : You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ';WITH convs AS ( select c.id, c.title, c.seen, c.id_receiver, c.id_send' at line 1
when i use this query :
$query = ";WITH convs AS (
select c.id, c.title, c.seen, c.id_receiver, c.id_sender
from conversations c
)
select id, title, seen, id_receiver, id_sender
from convs
where id_receiver = '5'
order by title desc limit 0,25";
$res = mysqli_query($connection ,$query);
Am i missing something ?
Your help would be much appreciated.
PS : i minimised the query to make it simple for this context, if you help me find the solution, i may have another problem with the full query. So i might come back to you for more help. Thank's in advance.
EDIT (WHOLE QUERY)
$query = "WITH convs AS (
select c.id, c.title, c.seen, c.id_receiver, c.id_sender,
(select max(date) from messages where id_conversation = c.id and id_user <> '$iduser') as last_msg,
(select top 1 id_user from messages where id_conversation = c.id and id_user <> '$iduser' order by date desc) as last_user,
(select count(distinct id_user) from messages where id_conversation = c.id) as nbruser,
(select count(*) from messages where id_conversation = c.id) as nbrmsg,
(select username from users where id = c.id_sender) as sender, (select username from users where id = c.id_receiver) as receiver,
(select count(*) from deleted_conversations where id_user='$iduser' and id_conversation=c.id) as deleted,
from conversations c
)
select id, title, seen, id_receiver, id_sender, receiver, sender, last_msg, last_user, deleted, nbruser, nbrmsg
from convs
where (id_receiver = '$iduser' or (id_sender == '$iduser' and nbruser > 1)) and deleted = 0
order by last_msg desc limit $pageLimit,$REC_PER_PAGE";
What pushed me to use CTE is the need of using aliases in where clause. And as you can see i have many of them.
Can you give me an example of how to use views/temporary tables to achieve my purpose ?
MySQL/MariaDB doesn't support CTEs. Plus, it is entirely unnecessary in this case:
select id, title, seen, id_receiver, id_sender
from conversations c
where id_receiver = '5'
order by ?? desc
limit 0, 25;
Note: You need to specify the column for the order by as well.
For more complex examples, you can use subqueries, views, and/or temporary tables.
CTEs are quite similar to Derived Tables:
select id, title, seen, id_receiver, id_sender, receiver, sender, last_msg, last_user, deleted, nbruser, nbrmsg
FROM
(
select c.id, c.title, c.seen, c.id_receiver, c.id_sender,
(select max(date) from messages where id_conversation = c.id and id_user <> '$iduser') as last_msg,
(select top 1 id_user from messages where id_conversation = c.id and id_user <> '$iduser' order by date desc) as last_user,
(select count(distinct id_user) from messages where id_conversation = c.id) as nbruser,
(select count(*) from messages where id_conversation = c.id) as nbrmsg,
(select username from users where id = c.id_sender) as sender, (select username from users where id = c.id_receiver) as receiver,
(select count(*) from deleted_conversations where id_user='$iduser' and id_conversation=c.id) as deleted,
from conversations c
) as convs
where (id_receiver = '$iduser' or (id_sender == '$iduser' and nbruser > 1)) and deleted = 0
order by last_msg desc limit $pageLimit,$REC_PER_PAGE
Related
select mt.from_user, mt.to_user, mt.group_id, g.name, g.created_by as adminuser,
msg.*,
(
SELECT id
from messages
where t.thread_id = thread_id
and id NOT IN (
SELECT message_id from message_deleted
where user_id=275 and status='deleted' )
order by CreatedDate DESC
limit 1
) as msgid,
(
SELECT CreatedDate
from messages
where t.thread_id = thread_id
and id NOT IN (
SELECT message_id from message_deleted
where user_id=275 and status='deleted' )
order by CreatedDate DESC
limit 1
) as msgDate
from user_thread as t
left join message_thread as mt ON t.thread_id = mt.id
left join group_master as g ON mt.group_id = g.id
left join group_member as gm ON gm.group_id = g.id
left join messages as msg ON t.thread_id = msg.thread_id
where ( gm.user_id=275
or msg.from_id=275
or msg.to_id=275
)
and t.status = 'Active'
group by mt.id
order by msgDate DESC
This takes about 50 sec.
In above code, I have try to split above query and note that below subquery take too much time to execute. Can I convert subquery into join. please help me. I am stuck.please note that all tables which are joined are necessary.
(
SELECT id
from messages
where t.thread_id = thread_id
and id NOT IN (
SELECT message_id from message_deleted
where user_id=275 and status='deleted' )
order by CreatedDate DESC
limit 1
) as msgid,
(
SELECT CreatedDate
from messages
where t.thread_id = thread_id
and id NOT IN (
SELECT message_id from message_deleted
where user_id=275 and status='deleted' )
order by CreatedDate DESC
limit 1
) as msgDate
First, You are misusing a notorious MySQL extension to GROUP BY. This will probably cause your results to be unpredictable. Read this. https://dev.mysql.com/doc/refman/5.7/en/group-by-handling.html
Second, You have a couple of nested dependent subqueries. The first of them is this.
(select id
from messages
where t.thread_id = thread_id
and id NOT IN (select message_id
from message_deleted
where user_id=275
and status='deleted')
order by CreatedDate DESC limit 1) as msgid
Such nested dependent subqueries perform notoriously badly. They're even worse when they contain LIMIT clauses. Your route to fixing this is refactoring into an independent query and then JOINing it.
This may work as a replacement for the query to find the most recent undeleted message on the thread.
SELECT MAX(m.id) id, m.thread_id
FROM messages m
LEFT JOIN message_deleted d
ON m.id = d.id
AND d.user_id = 275
AND d.status = 'deleted'
WHERE d.id IS NULL
GROUP BY m.thread_id
This uses the LEFT JOIN .... IS NULL pattern in place of NOT IN. It's faster. It uses the MAX(id) method of finding the most recent row in a table in place of the ORDER BY CreatedDate DESC LIMIT 1 method, which is also much faster. It's good because it's guaranteed to generate either 0 or 1 row per value of thread_id. That means you can use it in a LEFT JOIN ... ON ... thread_id operation and not add any rows to your result set.
You can test this subquery by running it. Then you JOIN it, as if it were a table, to the rest of your query, something like this.
SELECT whatever,
q.id, r.CreatedDate
FROM whatever
LEFT JOIN (
SELECT MAX(m.id) id, m.thread_id
FROM messages m
LEFT JOIN message_deleted d
ON m.id = d.id
AND d.user_id = 275
AND d.status = 'deleted'
WHERE d.id IS NULL
GROUP BY m.thread_id
) q ON q.id = t.id
LEFT JOIN messages r ON r.id = q.id
The second LEFT JOIN operation here is used to retrieve the CreatedDate value of the newest undeleted message from the messages table.
I'm trying to make a internal web based message system, with a *amp system, primarily for learning purposes. I don't know if this is a trivial topic, but I'm having difficulties so please bear with me.
The goal is to list all the contacts ordered by the last message sent / received.
Currently without sorting it the SQL looks like this
$query = "SELECT username, user.id as user_id,
(SELECT COUNT(message_read)
FROM message_user
WHERE message_read = 0
AND sent_id = user_id
AND receive_id = {$userId}) as unread
FROM user
WHERE user.id IN
(SELECT contact_id FROM allowed_contact WHERE user_id = {$userId})
;";
The structure of the tables are:
The user table has an id,
That links to the message_user table which has a sent_id and a receive_id,
The message_user has a message_id that corresponds to the message.id,
The message table has a timestamp.
I would like this to be done in SQL but if it comes down to PHP I resign to resort to that.
This works.
SELECT `u`.`id` AS user_id, username,
(SELECT COUNT(message_user.message_read)
FROM message_user
WHERE message_user.message_read = 0
AND sent_id = user_id
AND receive_id = {$userId}) as unread
FROM `user` AS `u`
LEFT JOIN `message_user` AS `mu`
ON
(CASE WHEN `u`.`id` != {$userId}
THEN `u`.`id` = `mu`.`sent_id`
WHEN `mu`.`sent_id` = {$userId} AND `mu`.`receive_id` = {$userId}
THEN `u`.`id` = `mu`.`sent_id`
END)
OR
(CASE WHEN `u`.`id` != {$userId}
THEN `u`.`id` = `mu`.`receive_id`
END)
LEFT JOIN `message` AS `m` ON `m`.`id` = `mu`.`message_id`
WHERE u.id IN
(SELECT contact_id FROM allowed_contact WHERE user_id = {$userId})
GROUP BY u.id
ORDER BY MAX(`m`.`timestamp`) DESC;
This broke down the problem I was having.
#Andreas thanks for time and help.
Use 2 LEFT JOIN with a DISTINCT (untested):
SELECT DISTINCT `u`.`id`
FROM `user` AS `u`
LEFT JOIN `message_user` AS `mu` ON `u`.`id` = `mu`.`sent_id` OR `u`.`id` = `mu`.`receive_id`
LEFT JOIN `message` AS `m` ON `m`.`id` = `mu`.`message_id`
ORDER BY `m`.`timestamp` DESC;
i need speed up this query for list latest messages. This query running too long (eg. 10 seconds ...)
SELECT datas.uid,
datas.message,
datas.date,
CONCAT(conv.first_name, ' ', conv.last_name) AS conversation_name
FROM (SELECT m.message_id,
m.message,
IF (m.from_uid = 1, m.to_uid, m.from_uid) AS uid,
m.readed,
m.sended AS `date`
FROM users u
LEFT JOIN messages m
ON m.from_uid = u.user_id
WHERE m.message_id IN (SELECT MAX(message_id)
FROM messages
WHERE to_uid = 1
OR from_uid = 1
GROUP BY LEAST(from_uid, to_uid),
GREATEST(from_uid, to_uid))) datas
LEFT JOIN users conv
ON conv.user_id = datas.uid
ORDER BY datas.date DESC
LIMIT 5
This query use 2 tables (users and messages).
Table users:
user_id (primary, autoincrement)
login
pass
first_name
last_name
....
Table messages:
message_id (primary, autoincrement)
from_uid (sender message, reference to table users -> user_id)
to_uid (receiver message, reference to table users -> user_id)
sended (timestamp)
message (varchar)
EDIT
I added indexes to messages:
- from_uid
- to_uid
- sended
and this is without efect...
Try creating indexed on the id's you're checking.
In this case you might want to create an index on: conv.user_id, datas.uid, m.message_id, messages.to_uid, messages.from_uid, and datas.date might be a good idea as well, since you're sorting on that.
Add indexes on from_uid and to_uid to speed up the SELECT MAX(message_id) subquery. Otherwise, it has to do a full scan of the table.
I would try and remove the sub query(s)
You can clean it up a bit by joining against users twice when getting the user details from te from and to uid. This way the joins can use indexes effectively. Then just use IF in the SELECT to decide which one to return:-
SELECT IF (m.from_uid = 1, m.to_uid, m.from_uid) AS uid,
m.message,
m.sended AS `date`,
IF (m.from_uid = 1, CONCAT(to_conv.first_name, ' ', to_conv.last_name), CONCAT(from_conv.first_name, ' ', from_conv.last_name)) AS conversation_name
FROM users u
LEFT JOIN messages m
ON m.from_uid = u.user_id
LEFT JOIN users to_conv
ON to_conv.user_id = m.to_uid
LEFT JOIN users from_conv
ON from_conv.user_id = m.from_uid
WHERE m.message_id IN
(
SELECT MAX(message_id)
FROM messages
WHERE to_uid = 1
OR from_uid = 1
GROUP BY LEAST(from_uid, to_uid),
GREATEST(from_uid, to_uid)
)
ORDER BY date DESC
LIMIT 5
The sub query to check the message id is a bit more difficult to remove. Generally IN performs badly. Might be worth changing it to use EXISTS (although this will require the check in the HAVING clause which might not be good)
SELECT IF (m.from_uid = 1, m.to_uid, m.from_uid) AS uid,
m.message,
m.sended AS `date`,
IF (m.from_uid = 1, CONCAT(to_conv.first_name, ' ', to_conv.last_name), CONCAT(from_conv.first_name, ' ', from_conv.last_name)) AS conversation_name
FROM users u
LEFT JOIN messages m
ON m.from_uid = u.user_id
LEFT JOIN users to_conv
ON to_conv.user_id = m.to_uid
LEFT JOIN users from_conv
ON from_conv.user_id = m.from_uid
WHERE EXISTS
(
SELECT MAX(message_id) AS max_message_id
FROM messages
WHERE to_uid = 1
OR from_uid = 1
GROUP BY LEAST(from_uid, to_uid), GREATEST(from_uid, to_uid)
HAVING m.message_id = max_message_id
)
ORDER BY date DESC
LIMIT 5
I have two type of message, one is private message and another is credit message are inserting into two different table. Now I'm trying to fetch the data.
SELECT * ,(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'like') AS likes,
(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'dislike') AS dislikes
FROM messages m
WHERE 1 #and hidden is null
and recipient_id = 1
ORDER BY datetime DESC
and
SELECT * ,(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'like') AS likes,
(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'dislike') AS dislikes
FROM private_messages m
WHERE 1 #and hidden is null
and recipient_id = 1
ORDER BY datetime DESC
Now want to merge them into one query one extra parameter will show its private message or credit message.
If the existing queries do what you want/need, UNION will make it pretty simple to combine them, something like;
SELECT * FROM (
SELECT is_private 0, <field1>,<field2>,<field3>, ... ,(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'like') AS likes,
(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'dislike') AS dislikes
FROM messages m
WHERE 1 #and hidden is null
and recipient_id = 1
UNION ALL
SELECT 1, <field1>, <field2>, <field3>, ... ,(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'like') AS likes,
(SELECT COUNT(*)
FROM votes
WHERE message_id = m.message_id
AND vote_type = 'dislike') AS dislikes
FROM private_messages m
WHERE 1 #and hidden is null
and recipient_id = 1
)
ORDER BY datetime DESC
Note that you need to select the same number/order of columns from both queries for the union to work. SELECT * makes it hard to verify if/that that is the case. If
You can use UNION to combine mysql query:
SELECT id FROM table_user
UNION
SELECT COUNT(vote) FROM table_vote
You can use multiple UNION query by UNION.
Like,
Query 1
UNION
Query 2
UNION
.....
.....
.....
Query n
I think the following is a much simpler way to express the logic:
select m.*, v.likes, v.dislikes
from (select v.message_id, sum(vote_type = 'like') AS likes, sum(vote_type = 'dislike') AS dislikes
from votes v
group by v.message_id
) v join
(select m.*, 'Message' as which
from messages
union all
select pm.*, 'PrivateMessage' as which
from private_messages pm
) m
on v.message_id = m.message_id;
I am trying to use two JOIN statements in one query,
$sqlsorgu = mysql_query("SELECT *, COUNT(*), AVG(clicks), AVG(scrolls), AVG(spent)
FROM track where referid='".$memberr."' GROUP BY referer ORDER BY id desc limit 15
JOIN
(
select id, country, num, num*100/total pct
from (SELECT id,country, count(*) as num
FROM track GROUP BY country
ORDER BY num desc limit 5) x
join (select count(*) total from track) y
) tc on t.id = tc.id") or die(mysql_error());
but I am getting this 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 'JOIN ( select id, country, num, num*100/total pct from (SELECT id,country' at line 1
What is the correct way to use it ?
GROUP BY/ WHERE/ Order by come after join statements. Try reording like:
"SELECT *, COUNT(*), AVG(clicks), AVG(scrolls), AVG(spent)
FROM track t
JOIN
(
select id, country, num, num*100/total pct
from (SELECT id,country, count(*) as num
FROM track GROUP BY country
ORDER BY num desc limit 5) x
join (select count(*) total from track) y
) tc on t.id = tc.id
where referid='".$memberr."'
GROUP BY referer
ORDER BY tc.id desc limit 15