I have the following query which queries a table of sports results for the last 20 matches that involved a teams, returning goals conceeded in each of these matches.
SELECT *, `against` AS `goalsF` , `for` AS `goalsA`
FROM `matches` , `teams` , `outcomes`
WHERE (
`home_team_id`=7 AND `matches`.away_team_id = `teams`.team_id
OR
`away_team_id`=7 AND `matches`.home_team_id = `teams`.team_id
)
AND `matches`.score_id = `outcomes`.outcome_id
ORDER BY `against', `date` DESC
LIMIT 0 , 20
I want sort the results by goals conceeded and then within each group of goals conceeded by date so for example.
the first 4 results where goals conceded=1 in date order
then the next 3 might be results where conceded=2 in date order
I have tried ORDER by date,against - this gives me a strict date order
I have tried ORDER by against,date - this gives me matches beyond the last 20
Is it possible to do what I want to do?
Thanks everyone, I found this worked. This solution was posted by another user but then was removed, not sure why?
SELECT * FROM (
SELECT *, `against` AS `goalsF` , `for` AS `goalsA`
FROM `matches` , `teams` , `outcomes`
WHERE (
`home_team_id`=7 AND `matches`.away_team_id = `teams`.team_id
OR
`away_team_id`=7 AND `matches`.home_team_id = `teams`.team_id
)
AND `matches`.score_id = `outcomes`.outcome_id
ORDER by `goalsF`
LIMIT 0 , 20
) res
ORDER BY `date` DESC
If you want to limit by date, add the date range you are looking for into your WHERE clause and then order by the number of goals conceded.
Related
Does anyone know what's wrong with this query?
This works perfectly on its own:
SELECT * FROM
(SELECT * FROM data WHERE site = '".$id."'
AND disabled = '0'
AND carvotes NOT LIKE '0'
AND (time > ( now( ) - INTERVAL 14 DAY ))
GROUP BY car ORDER BY carvotes DESC LIMIT 0 , 10)
X order by time DESC
So does this:
SELECT * FROM data WHERE site = '".$id."' AND disabled = '0' GROUP BY car DESC ORDER BY time desc LIMIT 0 , 30
But combining them like this:
SELECT * FROM data WHERE site = '".$id."' AND disabled = '0' AND car NOT IN (SELECT * FROM
(SELECT * FROM data WHERE site = '".$id."'
AND disabled = '0'
AND carvotes NOT LIKE '0'
AND (time > ( now( ) - INTERVAL 14 DAY ))
GROUP BY car ORDER BY carvotes DESC LIMIT 0 , 10)
X order by time DESC) GROUP BY car DESC ORDER BY time desc LIMIT 0 , 30
Gives errors. Any ideas?
Please try the following...
$result = mysqli_query( $con,
"SELECT *
FROM data
WHERE site = '" . $id .
"' AND disabled = '0'
AND car NOT IN ( SELECT car
FROM ( SELECT car,
carvotes
FROM data
WHERE site = '" . $id .
"' AND disabled = '0'
AND carvotes NOT LIKE '0'
AND ( time > ( NOW( ) - INTERVAL 14 DAY ) )
GROUP BY car
ORDER BY carvotes DESC
LIMIT 10 ) X
)
GROUP BY car
ORDER BY time DESC
LIMIT 30" );
The main cause of your problem is that with car NOT IN ( SELECT * FROM ( SELECT *... you are trying to compare each record's value of car with each row returned by your subquery. IN requires you to have the same number of fields on both sides of the comparison. By using SELECT * at both levels of the subquery you were ensuring that the right side of the comparison had however many fields are in data versus your single field on the left, which confused MySQL.
Since you are aiming to compare to a single field, namely car, our subquery has to select just the car field from its dataset. Since the sort order of the subquery's results has no effect upon the IN comparison, and since our innermost query will be returning just car, I have removed the outer level of the subquery.
Beyond changing the first part of the subquery to SELECT car, the only other change that I have made to the subquery is to change LIMIT 0, 10 to LIMIT 10. The former means limit to the the 10 records that are offset by 0 from the first record. This is useful if you want records 6 to 15, but redundant for 1 to 10 as LIMIT 10 has the same affect and is slightly simpler. Ditto for LIMIT 0, 30 at the end of your overall statement.
As for the main body of the statement, I have not made any attempt to specify what fields (or aggregate functions of those fields) should be returned since you have made no statement indicating what your requirements / preferences are. If you are satisfied that GROUP BY has left you with a still valid set of values, then all the good, but if not then I recommend that you rewrite your Question to be specific about that detail.
By default, MySQL sorts the data subjected to a GROUP BY into ascending order, but if an ORDER BY clause is also present then it overrides the GROUP BY's sort pattern. As such, there is no benefit to specifying DESC after either of your GROUP BY car clauses, so I have removed it where it occurs.
Interesting Sidenote : You can override a GROUP BY's sort by specifying ORDER BY NULL.
If you have any questions or comments, then please feel free to post a Comment accordingly.
Further Reading
https://dev.mysql.com/doc/refman/5.7/en/order-by-optimization.html - on optimising your ORDER BY sorting
https://dev.mysql.com/doc/refman/5.7/en/select.html - on the SELECT statement's syntax - specifically the parts to do with LIMIT.
https://www.w3schools.com/php/php_mysql_select_limit.asp - a simpler explanation of LIMIT
This is your query:
SELECT *
FROM data
WHERE site = '".$id."' AND disabled = '0' AND
car NOT IN (SELECT *
FROM (SELECT *
FROM data
WHERE site = '".$id."' AND
disabled = '0' AND
carvotes NOT LIKE '0' AND
(time > ( now( ) - INTERVAL 14 DAY ))
GROUP BY car
ORDER BY carvotes DESC
LIMIT 0 , 10
) x
ORDER BY time DESC
)
GROUP BY car DESC
ORDER BY time desc
LIMIT 0 , 30 ;
Several comments:
Do not wrap integer constants in single quotes. This can mislead people. This can mislead optimizers.
Do not use string functions on integers (such as like). Same reason.
NOT IN with subqueries is dangerous. The construct does not handle NULL values the way you expect. Use NOT EXISTS or LEFT JOIN instead.
When using subqueries, ORDER BY is almost never appropriate.
Never use SELECT * with GROUP BY. It is just wrong. Happily, MySQL 5.7 has changed its defaults to reject this anti-pattern
So, a better way to write this query is something like this:
SELECT d.car, MAX(time) as time
FROM data d LEFT JOIN
(SELECT d2.*
FROM data d2
WHERE d2.site = '".$id."' AND
d2.disabled = 0 AND
d2.carvotes NOT LIKE 0 AND
(d2.time > ( now( ) - INTERVAL 14 DAY ))
GROUP BY d2.car
ORDER BY carvotes DESC
LIMIT 0 , 10
) car10
ON d.car = car10.car
WHERE d.site = '".$id."' AND d.disabled = 0' AND
car10.car IS NOT NULL
GROUP BY car DESC
ORDER BY MAX(time) desc
LIMIT 0 , 30 ;
Alternatively, use SELECT * and remove the GROUP BY in the outer query.
SELECT * FROM (
SELECT * FROM cars WHERE site = '5'
ORDER BY cost DESC LIMIT 0 , 10
)
ORDER BY time
How would I execute a sql query like this? So first it selects the 10 cars with the highest cost, THEN it reorders those 10 cars by what time they were added to the DB.
I tried to figure it out but I just cannot get a grip on the syntax :P
Just give an alias to the sub-query.
SELECT * FROM (
SELECT * FROM `cars` WHERE `site` = '5'
ORDER BY `cost` DESC LIMIT 0 , 10
)t
ORDER BY `time`;
This query will give you the desired results
SELECT * FROM ( SELECT * FROM cars WHERE site = 5
ORDER BY cost DESC LIMIT 0 , 10 ) as t ORDER BY time
I am working with a table of items with expiration dates,these items are assigned to users.
I want to get for each user,the highest expiration date.The issue here is that default items are initialized with a '3000/01/01' expiration date that should be ignored if another item exists for that user.
I've got a query doing that:
SELECT
user_id as UserId,
CASE WHEN (YEAR(MAX(date_expiration)) = 3000)
THEN (
SELECT MAX(temp.date_expiration)
FROM user_items temp
WHERE YEAR(temp.date_expiration) <> 3000 and temp.user_id = UserId
)
ELSE MAX(date_expiration)
END as date_expiration
FROM user_items GROUP BY user_id
This works, but the query inside THEN block is killing performance a bit and it is a huge table.
So,Is there a better way to ignore the default date from the MAX operation when entering the CASE condition?
SELECT user_id,
COALESCE(
MAX(CASE WHEN YEAR(date_expiration) = 3000 THEN NULL ELSE date_expiration END),
MAX(date_expiration)
)
FROM user_items
GROUP BY
user_id
If there are few users but lots of entries per user in your table, you can try improving your query yet a little more:
SELECT user_id,
COALESCE(
(
SELECT date_expiration
FROM user_items uii
WHERE uii.user_id = uid.user_id
AND date_expiration < '3000-01-01'
ORDER BY
user_id DESC, date_expiration DESC
LIMIT 1
),
(
SELECT date_expiration
FROM user_items uii
WHERE uii.user_id = uid.user_id
ORDER BY
user_id DESC, date_expiration DESC
LIMIT 1
)
)
FROM (
SELECT DISTINCT
user_id
FROM user_items
) uid
You need an index on (user_id, date_expiration) for this to work fast.
I have a table in this structure:
editor_id
rev_user
rev_year
rev_month
rev_page
edit_count
here is the sqlFiddle: http://sqlfiddle.com/#!2/8cbb1/1
I need to surface the 5 most active editors during March 2011 for example - i.e. for each rev_user - sum all of the edit_count for each rev_month and rev_year to all of the rev_pages.
Any suggestions how to do it?
UPDATE -
updated fiddle with demo data
You should be able to do it like this:
Select the total using SUM and GROUP BY, filtering by rev_year and rev_month
Order by the SUM in descending order
Limit the results to the top five items
Here is how:
SELECT * FROM (
SELECT rev_user, SUM(edit_count) AS total_edits
FROM edit_count_user_date
rev_year='2006' AND rev_month='09'
GROUP BY rev_user
) x
ORDER BY total_edits DESC
LIMIT 5
Demo on sqlfiddle.
Surely this is as straightforward as :
SELECT rev_user, SUM(edit_count) as TotalEdits
FROM edit_count_user_date
WHERE rev_month = 'March' and rev_year = '2014'
GROUP BY rev_user
ORDER BY TotalEdits DESC
LIMIT 5;
SqlFiddle here
May I also suggest using a more appropriate DATE type for the year and month storage?
Edit, re new Info
The below will return all edits for the given month for the 'highest' MonthTotal editor, and then re-group the totals by the rev_page.
SELECT e.rev_user, e.rev_page, SUM(e.edit_count) as TotalEdits
FROM edit_count_user_date e
INNER JOIN
(
SELECT rev_user, rev_year, rev_month, SUM(edit_count) AS MonthTotal
FROM edit_count_user_date
WHERE rev_month = '09' and rev_year = '2010'
GROUP BY rev_user, rev_year, rev_month
ORDER BY MonthTotal DESC
LIMIT 1
) as x
ON e.rev_user = x.rev_user AND e.rev_month = x.rev_month AND e.rev_year = x.rev_year
GROUP BY e.rev_user, e.rev_page;
SqlFiddle here - I've adjusted the data to make it more interesting.
However, if you need to do this across several months at a time, it will be more difficult given MySql's lack of partition by / analytical windowing functions.
I have the following code:
SELECT q25, (
(
AVG( q1 ) + AVG( q2 ) + AVG( q3 ) ) /3 ) AS Overall
FROM t_results
WHERE brand = 'XYZ'
AND DATE = 'MAY2012'
GROUP BY q25
ORDER BY Overall
DESC LIMIT 1
If there is no data found by the query phpmyadmin returns the following message (which is quite correct):
MySQL returned an empty result set (i.e. zero rows). ( Query took 0.0178 sec )
However, what I'd like is to actually return a NULL value, is this possible? I appreciate this might not be best practise but I'm working with inherited code and this might be the simplist and quickest route to a solution.
Thanks as always,
H.
Create a table with exactly one row. Then you can use left join to achieve the desired NULL result.
CREATE TABLE dummy (d TINYINT NOT NULL);
INSERT INTO dummy SET d = 1;
SELECT q25,
( ( AVG( q1 ) + AVG( q2 ) + AVG( q3 ) ) /3 ) AS Overall
FROM dummy LEFT JOIN t_results
ON brand = 'XYZ'
AND DATE = 'MAY2012'
GROUP BY q25
ORDER BY Overall DESC
LIMIT 1
You can also replace the dummy table with a subquery:
SELECT q25,
( ( AVG( q1 ) + AVG( q2 ) + AVG( q3 ) ) /3 ) AS Overall
FROM (SELECT 1) AS dummy LEFT JOIN t_results
ON brand = 'XYZ'
AND DATE = 'MAY2012'
GROUP BY q25
ORDER BY Overall DESC
LIMIT 1
Tested this via sqlfiddle, where you can also experiment with alternatives.
The conditions selecting the result, which used to be in the WHERE clause, now have to go into the ON clause. Otherwise the left join would produce non-NULL rows which would be removed by the WHERE, instead of generating a single NULL row if no matching row could be found. If there were no WHERE conditions in the original query, ON 1 could be used to express any row matches.
You can use a UNION combined with a LIMIT to supply the NULL values:
(SELECT q25,
(AVG(q1) + AVG(q2) + AVG(q3))/3 AS Overall
FROM t_results
WHERE brand = 'XYZ'
AND DATE = 'MAY2012'
GROUP BY q25
ORDER BY Overall DESC
LIMIT 1
)
UNION ALL
(SELECT NULL, NULL)
LIMIT 1;
This only works when you know that the first query will never yield more than one result, though. Which is the case here, so this might be the best solution for you, but the approach given in my other answer is more general.
There is a fiddle for this to experiment with.
The coalesce() function can be used to return the first non-null value from a number of comma separated columns or strings. The values/columns are evaluated left to right, so if you want to pop a string into the arguments that isn't null, make sure you place it to the right of the columns that you are testing against.
select
coalesce(
(
SELECT
q25
FROM
t_results
WHERE
brand = 'XYZ'
AND DATE = 'MAY2012'
GROUP BY
q25
LIMIT 1
), 'null') as q25,
coalesce(
(
SELECT
((AVG( q1 ) + AVG( q2 ) + AVG( q3 ) ) /3 ) AS Overall
FROM t_results
WHERE
brand = 'XYZ'
AND DATE = 'MAY2012'
LIMIT 1
), 'null') as Overall
from
t_results
group by
1, 2;
If you don't have data that matches your where clause, this will return null, null as a row.