I have managed to hack an SQL Query together and it was working until I realised some members in the database have null names due to the plugin we are using removes non-ascii names. I am displaying these stats on my page and having someone with no name doesn't work too well. I know how to not display NULL when using the WHERE clause but i'm not too sure when no WHERE clause is used.
What I have so far -
SELECT player_stats.player_name, COUNT(player_kill.killer)
FROM player_stats
LEFT JOIN player_kill ON player_stats.player_id = player_kill.killer
GROUP BY player_stats.player_name
HAVING COUNT(player_kill.killer) > 1
ORDER BY COUNT(player_kill.killer) DESC;
The WHERE clause goes between all the JOIN clauses and GROUP BY. If WHERE player_name IS NOT NULL isn't working, the names are probably empty strings, not NULL, so you need to check for that as well.
SELECT s.player_name, COUNT(*) AS count
FROM player_stats AS s
INNER JOIN player_kill AS k ON s.player_id = k.killer
WHERE s.player_name IS NOT NULL AND s.player_name != ''
GROUP BY s.player_name
ORDER BY count DESC;
Also, if you don't want to get 0 counts, use INNER JOIN rather than LEFT JOIN.
If you don't want to change your query to much you can replace the players name by checking if it's null.
SELECT ISNULL(s.player_name, "RandomPlayer"), COUNT(*) AS count
FROM player_stats AS s
INNER JOIN player_kill AS k ON s.player_id = k.killer
WHERE s.player_name IS NOT NULL AND s.player_name != ''
GROUP BY s.player_name
ORDER BY count DESC;
https://msdn.microsoft.com/en-us/library/ms184325.aspx
Related
$query = "SELECT a.comment_user_id as main_id, a.comment_date as timestamp, a.comment_content as content, a.comment_link_id as link_unique, a.comment_id as status, NULL as url, b.user_login as ulogin, b.user_avatar_source as uavatar, c.link_title as ltitle, NULL as desc FROM kliqqi_comments as a WHERE comment_user_id IN ('$following2')
LEFT JOIN kliqqi_users as b ON a.comment_user_id = b.user_id
LEFT JOIN kliqqi_links as c ON a.comment_user_id = c.link_author
ORDER BY timestamp DESC LIMIT 10";
$result = mysqli_query($db_conx, $query);
$row = $result->fetch_array(MYSQLI_ASSOC);
Can anybody tell me what's wrong with the code? It is always returning this error:
Fatal error: Call to a member function fetch_assoc() on boolean
Boolean means this query is not getting executed due to some error in $query variable which I am unable to figure out.
$following is an array. kliqqi_comments alias a, kliqqi_users alias b, kliqqi_links alias c. I am storing all the other fields as alias too. There is no typo or any other silly mistake. I've checked it thoroughly.
UPDATE:
I'm updating this thread because my query actually has many parts and many users may find it helpful.
$query = "SELECT a.comment_user_id as main_id, a.comment_date as timestamp2, a.comment_content as content, a.comment_link_id as link_unique, a.comment_id as status, b.user_login as ulogin, b.user_avatar_source as uavatar, c.link_title as ltitle FROM kliqqi_comments a
LEFT JOIN kliqqi_users b ON a.comment_user_id = b.user_id
LEFT JOIN kliqqi_links c ON a.comment_link_id = c.link_id
WHERE comment_user_id IN ('$following')
UNION ALL
SELECT d.link_author as main_id, d.link_date as timestamp2, d.link_status as content, d.link_id as link_unique, NULL as status, e.user_login as ulogin, e.user_avatar_source as uavatar, d.link_title as ltitle FROM kliqqi_links d
LEFT JOIN kliqqi_users e ON d.link_author = e.user_id
WHERE link_author IN ('$following') AND link_status IN ('new','published')
UNION ALL
SELECT f.vote_user_id as main_id, f.vote_date as timestamp2, f.vote_value as content, f.vote_link_id as link_unique, NULL as status, g.user_login as ulogin, g.user_avatar_source as uavatar, h.link_title as ltitle FROM kliqqi_votes f
LEFT JOIN kliqqi_users g ON f.vote_user_id = g.user_id
LEFT JOIN kliqqi_links h ON f.vote_link_id = h.link_id
WHERE vote_user_id IN ('$following')
ORDER BY timestamp2 DESC LIMIT 30";
What does it do?
I've 3 tables: kliqqi_links, kliqqi_users, kliqqi_votes
UNION ALL
All of them have a timestamp field.
I wanted to fetch contents from these 3 tables combined in decreasing order of timestamp. And to do so, I used UNION ALL (UNION can also be used here but UNION has to run duplicate checks so it's better to avoid it if you can.). But UNION ALL works only when all of the tables have same number of fields. So, I created NULL elements for equating the numbers.
It is to be noted that there is no restriction of datatype for uniting respective fields. But since I had to use timestamp for sequence, I kept them together.
Alias
Since all the respective fields have different names in different tables, I used alias to avoid confusion. Without alias, results are stored in fields mentioned in first SELECT statement which would be a mess.
Multiple LEFT JOIN
Now, I wanted to grab some data from other tables for each SELECT query.
e.g. for kliqqi_comments (first SELECT statement), I wanted to grab user data for the person who made the comment from kliqqi_users plus I wanted to fetch the link where this comment was made from kliqqi_links table. So, I used left join with kliqqi_comments query where comment_user_id from kliqqi_comments equals to user_id from kliqqi_users and comment_link_id from kliqqi_comments equals link_id from kliqqi_links.
Notice that I managed to equate fields in all 3 statements for UNION ALL.
WHERE IN
$following is comma separated array to ensure that it returns result from the people user is following.
ORDER BY DESC, LIMIT
To order by timestamp and LIMIT output result.
That's it.
The where clauses should come after the join clauses, not before them. Additionally, desc and timestamp are reserved words. If you absolutely must use them as a column aliases, you need to escape them:
SELECT a.comment_user_id as main_id,
a.comment_date as `timestamp`, -- Notice the escaping
a.comment_content as content,
a.comment_link_id as link_unique,
a.comment_id as status,
NULL as url,
b.user_login as ulogin,
b.user_avatar_source as uavatar,
c.link_title as ltitle,
NULL as `desc` -- Notice the escaping
FROM kliqqi_comments as a
LEFT JOIN kliqqi_users as b ON a.comment_user_id = b.user_id
LEFT JOIN kliqqi_links as c ON a.comment_user_id = c.link_author
WHERE comment_user_id IN ('$following2') -- Where clause after the joins
ORDER BY `timestamp` DESC LIMIT 10";
I have been researching this for hours and the best code that I have come up with is this from an example i found on overstack. I have been through several derivations but the following is the only query that returns the correct data, the problem is it takes over 139s (more than 2 minutes) to return only 30 rows of data. Im stuck. (life_p is a 'likes'
SELECT
logos.id,
logos.in_gallery,
logos.active,
logos.pubpriv,
logos.logo_name,
logos.logo_image,
coalesce(cc.Count, 0) as CommentCount,
coalesce(lc.Count, 0) as LikeCount
FROM logos
left outer join(
select comments.logo_id, count( * ) as Count from comments group by comments.logo_id
) cc on cc.logo_id = logos.id
left outer join(
select life_p.logo_id, count( * ) as Count from life_p group by life_p.logo_id
) lc on lc.logo_id = logos.id
WHERE logos.active = '1'
AND logos.pubpriv = '0'
GROUP BY logos.id
ORDER BY logos.in_gallery desc
LIMIT 0, 30
I'm not sure whats wrong. If i do them singularly meaningremove the coalece and one of the joins:
SELECT
logos.id,
logos.in_gallery,
logos.active,
logos.pubpriv,
logos.logo_name,
logos.logo_image,
count( * ) as lc
FROM logos
left join life_p on life_p.logo_id = logos.id
WHERE logos.active = '1'
AND logos.pubpriv = '0'
GROUP BY logos.id
ORDER BY logos.in_gallery desc
LIMIT 0, 30
that runs in less than half a sec ( 2-300 ms )....
Here is a link to the explain: https://logopond.com/img/explain.png
MySQL has a peculiar quirk that allows a group by clause that does not list all non-aggregating columns. This is NOT a good thing and you should always specify ALL non-aggregating columns in the group by clause.
Note, when counting over joined tables it is useful to know that the COUNT() function ignores NULLs, so for a LEFT JOIN where NULLs can occur don't use COUNT(*), instead use a column from within the joined table and only rows from that table will be counted. From these points I would suggest the following query structure.
SELECT
logos.id
, logos.in_gallery
, logos.active
, logos.pubpriv
, logos.logo_name
, logos.logo_image
, COALESCE(COUNT(cc.logo_id), 0) AS CommentCount
, COALESCE(COUNT(lc.logo_id), 0) AS LikeCount
FROM logos
LEFT OUTER JOIN comments cc ON cc.logo_id = logos.id
LEFT OUTER JOIN life_p lc ON lc.logo_id = logos.id
WHERE logos.active = '1'
AND logos.pubpriv = '0'
GROUP BY
logos.id
, logos.in_gallery
, logos.active
, logos.pubpriv
, logos.logo_name
, logos.logo_image
ORDER BY logos.in_gallery DESC
LIMIT 0, 30
If you continue to have performance issues then use a execution plan and consider adding indexes to suit.
You can create some indexes on the joining fields:
ALTER TABLE table ADD INDEX idx__tableName__fieldName (field)
In your case will be something like:
ALTER TABLE cc ADD INDEX idx__cc__logo_id (logo_id);
I dont really like it because ive always read that sub queries are bad and that joins perform better under stress, but in this particular case subquery seems to be the only way to pull the correct data in under half a sec consistently. Thanks for the suggestions everyone.
SELECT
logos.id,
logos.in_gallery,
logos.active,
logos.pubpriv,
logos.logo_name,
logos.logo_image,
(Select COUNT(comments.logo_id) FROM comments
WHERE comments.logo_id = logos.id) AS coms,
(Select COUNT(life_p.logo_id) FROM life_p
WHERE life_p.logo_id = logos.id) AS floats
FROM logos
WHERE logos.active = '1' AND logos.pubpriv = '0'
ORDER BY logos.in_gallery desc
LIMIT ". $start .",". $pageSize ."
Also you can create a mapping tables to speed up your query try:
CREATE TABLE mapping_comments AS
SELECT
comments.logo_id,
count(*) AS Count
FROM
comments
GROUP BY
comments.logo_id
) cc ON cc.logo_id = logos.id
Then change your code
left outer join(
should become
inner join mapping_comments as mp on mp.logo_id =cc.id
Then each time a new comment are added to the cc table you need to update your mapping table OR you can create a stored procedure to do it automatically when your cc table changes
I have this query
SELECT r.id, r.name, r.code, rv.votes
FROM tbl_rhythms AS r
LEFT JOIN
(SELECT rhythm_id, votes
FROM tbl_songs_rhythms
WHERE song_id = 1
ORDER BY votes DESC) AS rv
ON r.id = rv.rhythm_id
...which returns this result when executed in MySQL 5.6.20
3,Blues,blues, 2
4,Bollero,bollero, 1
1,Ballad,ballad, NULL
2,Slow,slow, NULL
5,Slow rocj,slowrock, NULL
6,Disco,disco, NULL
but when I execute the same query in MySQL 5.5.40-0ubuntu0.14.04.1
1,Ballad,ballad, NULL
2,Slow,slow, NULL
3,Blues,blues, 2
4,Bollero,bollero, 1
5,Slow rock,slowrock, NULL
6,Disco,disco, NULL
As you can see, the order is messed up.
Is it a bug of MySQL 5.5.40?
Your question has different results, but then you add "the order is messed up."
This is obviously true because the outer query has no order by. And, it is the order by in the outermost select that determines the ordering. You need to put the order by there:
SELECT r.id, r.name, r.code, rv.votes
FROM tbl_rhythms r LEFT JOIN
tbl_songs_rhythms rv
ON r.id = rv.rhythm_id AND rv.song_id = 1
ORDER BY rv.votes DESC;
This also should make the query more efficient, because it is not materializing a subquery and it can use an in dex on tbl_songs_rhythms(rhythm_id) for the join.
As for why balad,balad would get NULL in one case but 1 in the other -- I think that would be a data issue and has nothing to do with the structure of this query.
I have a problem with the ROLLUP, I have rows with null values, and the ROLLUP also returns null, how do I difference between the null values of the ROLLUP and the null values of the row?
The null in the rows exist because the column (group_name) is associated with a left join.
Here is my query:
SELECT gr.info,
HOUR(cdr.calldate) AS hour,
DATE(cdr.calldate) AS date,
COUNT(DISTINCT cdr.uniqueid) AS count,
pl.number,
IFNULL(ugr.group_name, "") AS group_name
FROM cdr
INNER JOIN callinfo AS ci
ON ci.uniqueid = cdr.uniqueid
LEFT JOIN users AS usr
ON usr.username = ci.agent
LEFT JOIN groups AS ugr
ON ugr.group_id = usr.group_id
INNER JOIN pstnline AS pl
ON ci.line = pl.number
INNER JOIN hunt_line AS gri
ON gri.pstnline_id = pl.pstnline_id
INNER JOIN hunt AS gr
ON gri.hunt_number = gr.number
WHERE cdr.calldate >='2012-12-01 00:00'
AND cdr.calldate <='2013-01-24 10:45'
GROUP BY group_name WITH ROLLUP
I see that in SQL Server exist a function called GROUPING, but in MySql doesn't exist, how can i achieve the same effect?
I think you can also do this in the query that you have, by changing the group by argument to:
group by ifnull(ugr.group_name, '')
Now, blanks will indicate NULLs from the outer join and NULLs will indicate rollup.
Can anyone see what is wrong with the below query?
When I run it I get:
#1064 - 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 'a where a.CompetitionID = Competition.CompetitionID' at line 8
Update Competition
Set Competition.NumberOfTeams =
(
SELECT count(*) as NumberOfTeams
FROM PicksPoints
where UserCompetitionID is not NULL
group by CompetitionID
) a
where a.CompetitionID = Competition.CompetitionID
The main issue is that the inner query cannot be related to your where clause on the outer update statement, because the where filter applies first to the table being updated before the inner subquery even executes. The typical way to handle a situation like this is a multi-table update.
Update
Competition as C
inner join (
select CompetitionId, count(*) as NumberOfTeams
from PicksPoints as p
where UserCompetitionID is not NULL
group by CompetitionID
) as A on C.CompetitionID = A.CompetitionID
set C.NumberOfTeams = A.NumberOfTeams
Demo: http://www.sqlfiddle.com/#!2/a74f3/1
Thanks, I didn't have the idea of an UPDATE with INNER JOIN.
In the original query, the mistake was to name the subquery, which must return a value and can't therefore be aliased.
UPDATE Competition
SET Competition.NumberOfTeams =
(SELECT count(*) -- no column alias
FROM PicksPoints
WHERE UserCompetitionID is not NULL
-- put the join condition INSIDE the subquery :
AND CompetitionID = Competition.CompetitionID
group by CompetitionID
) -- no table alias
should do the trick for every record of Competition.
To be noticed :
The effect is NOT EXACTLY the same as the query proposed by mellamokb, which won't update Competition records with no corresponding PickPoints.
Since SELECT id, COUNT(*) GROUP BY id will only count for existing values of ids,
whereas a SELECT COUNT(*) will always return a value, being 0 if no records are selected.
This may, or may not, be a problem for you.
0-aware version of mellamokb query would be :
Update Competition as C
LEFT join (
select CompetitionId, count(*) as NumberOfTeams
from PicksPoints as p
where UserCompetitionID is not NULL
group by CompetitionID
) as A on C.CompetitionID = A.CompetitionID
set C.NumberOfTeams = IFNULL(A.NumberOfTeams, 0)
In other words, if no corresponding PickPoints are found, set Competition.NumberOfTeams to zero.
For the impatient:
UPDATE target AS t
INNER JOIN (
SELECT s.id, COUNT(*) AS count
FROM source_grouped AS s
-- WHERE s.custom_condition IS (true)
GROUP BY s.id
) AS aggregate ON aggregate.id = t.id
SET t.count = aggregate.count
That's #mellamokb's answer, as above, reduced to the max.
You can check your eav_attributes table to find the relevant attribute IDs for each image role, such as;
Then you can use those to set whichever role to any other role for all products like so;
UPDATE catalog_product_entity_varchar AS `v` INNER JOIN (SELECT `value`,`entity_id` FROM `catalog_product_entity_varchar` WHERE `attribute_id`=86) AS `j` ON `j`.`entity_id`=`v`.entity_id SET `v`.`value`=j.`value` WHERE `v`.attribute_id = 85 AND `v`.`entity_id`=`j`.`entity_id`
The above will set all your 'base' roles to the 'small' image of the same product.