I have a MySQL table where I want part of it sorted differently. For instance, I want the following result set:
+----+
| id |
+----+
| 1 | #ascending
| 2 |
| 3 |
| 4 |
| 8 | #descending
| 7 |
| 6 |
| 5 |
+----+
I essentially want to do something like:
ORDER BY
WHEN id <= 4 THEN
id ASC
ELSE
id DESC
END;
which is of course nonsense. Is there a sensical equivalent? I’ve tried using UNION, but subquery order is ignored.
You can use a two stage ordering process; the first part orders by whether id is less than or equal to 4, and the second orders by either id (for id <= 4) or -id (for id > 4) so that values greater than 4 sort descending:
SELECT *
FROM data
ORDER BY id <= 4 DESC,
CASE WHEN id <= 4 THEN id ELSE -id END
Output:
id
1
2
3
4
8
7
6
5
Demo on SQLFiddle
Someone posted this answer but deleted it; I’m reposting because it’s still a valid answer.
Rather than working the order change into an ELSE clause, you can limit one rule to a subset and the next will apply to the rest:
ORDER BY id <= 4 DESC,
CASE WHEN id <= 4 THEN id END ASC,
id DESC;
Demo on SQLFiddle
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Trying to retrieve records by first summing their time_spent, then using max to retrieve the largest record by time. which seems to be working.
I need to now check if on the chance that the sum of time_spent are the same value for users (a tie, like in the example below, both users have time_spent as 10 so it should then select the user that has the latest post), if they are then I need to only get the user_id that was posted last (newer) using the created_at column. I just don't know what to use to do that check, is it a CASE, or IF Function? and if so where would it go in my query?
Here is a sql fiddle link: http://sqlfiddle.com/#!9/f24985/2
Table1 layout
+----+---------+-----------+---------+------------+------------+
| id | user_id | member_id | item_id | time_spent | created_at |
+----+---------+-----------+---------+------------+------------+
| 1 | 1 | 1 | 1 | 5 | 2019-06-01 |
| 2 | 2 | 1 | 1 | 1 | 2019-06-07 |
| 3 | 2 | 1 | 1 | 5 | 2019-06-08 |
| 4 | 2 | 1 | 2 | 4 | 2019-06-01 |
| 5 | 1 | 1 | 2 | 5 | 2019-06-07 |
+----+---------+-----------+---------+------------+------------+
Current SQL:
SELECT
MAX(attribute_time.sum_time), attribute_time.user_id
FROM (
SELECT
SUM(time_spent) AS sum_time, user_id
FROM
table1
WHERE
member_id = 1
AND item_id IN (1, 2)
AND (created_at BETWEEN '2019-06-1' AND '2019-06-30')
GROUP BY
user_id
ORDER BY
sum_time desc
) AS attribute_time;
In this example, both users have a total of 10 for time, currently returns the first record of the 2 and not based on the created_at date, which in this case, should be user 2.
Expected
+---------+
| user_id |
+---------+
| 2 |
+---------+
This is what you are looking for. http://sqlfiddle.com/#!9/a5306c/4/0
The MAX clause is problematic for sub-queries involving quantities unless you use some repetitive and verbose queries (DRY!), as seen in answer here: MySQL: Select MAX() from sub-query with COUNT() - it seems to decouple the rows, so you get the highest (max) sum_time with the wrong id (I thought I was seeing things, seemed so simple)
I used LIMIT to get around it. Sorting descending (the highest on top), and then LIMITing the result to 1 achieves the same thing as "Max".
Also - Im not sure if in event of a tie in max time you wanted to pick the earliest or latest record, but this picks the latest. I use MAX to pick the last day/time for each user, and orderby sum_of_time, then by date. If you want the opposite, sub MIN for MAX and/or DESC for ASC in the order-by. Regards! Thx for the exercise.
SELECT
SUM(time_spent) AS sum_time, user_id, MAX(created_at)
FROM
Table1
WHERE
member_id = 1
AND item_id IN (1, 2)
AND (created_at BETWEEN '2019-06-1' AND '2019-06-30')
GROUP BY
user_id
ORDER BY
sum_time DESC, created_at DESC
LIMIT 1
Try to use this it will give you user id 2
SELECT
MAX(attribute_time.sum_time), attribute_time.user_id
FROM (
SELECT
SUM(time_spent) AS sum_time, user_id
FROM
table1
WHERE
member_id = 1
AND item_id IN (1, 2)
AND (created_at BETWEEN '2019-06-1' AND '2019-06-30')
GROUP BY
user_id
ORDER BY
sum_time,user_id desc
) AS attribute_time;
We have a DB called transaction. It has user_id, date, value and so on. I use pagination in my query also. I have thousands of record in my table which has user_id equal to 2 or other value. put the user_id = 2 at the very last page.
I want to sort the result like this:
sort the results by date but if the user_id= 2 , put all results associated with the user_id= 2 at the end.
to be more clear, I show you what I want in the below.
-------------------------------------
| ID | user_id | date | ......
-------------------------------------
| 1 | 10 | 2018-10-20 |
-------------------------------------
| 2 | 11 | 2018-10-21 |
-------------------------------------
| 3 | 2 | 2018-10-22 |
-------------------------------------
| 4 | 2 | 2018-10-23 |
the results have to be like this:
first: ID = 2, second: ID = 1, third: ID = 4, last: ID = 3
tip *:
I use field function but unfortunately in vain.
ORDER BY FIELD(user_id, 2) DESC, date DESC
You may try using a CASE expression in your ORDER BY clause:
SELECT *
FROM yourTable
ORDER BY
CASE WHEN user_id = 2 THEN 1 ELSE 0 END,
date DESC;
I'm not sure if you want each group sorted by date ascending or descending. If you want ascending date order, then remove the DESC keyword at the end of my query.
I want to show first two top voted Posts then others sorted by id
This is table
+----+-------+--------------+--------+
| Id | Name | Post | Votes |
+====+=======+==============+========+
| 1 | John | John's msg | -6 |
| 2 |Joseph |Joseph's msg | 8 |
| 3 | Ivan | Ivan's msg | 3 |
| 4 |Natalie|Natalie's msg | 10 |
+----+-------+--------------+--------+
After query result should be:
+----+-------+--------------+--------+
| Id | Name | Post | Votes |
+====+=======+==============+========+
| 4 |Natalie|Natalie's msg | 10 |
| 2 |Joseph |Joseph's msg | 8 |
-----------------------------------------------
| 1 | John | John's msg | -6 |
| 3 | Ivan | Ivan's msg | 3 |
+----+-------+--------------+--------+
I have 1 solution but i feel like there is better and faster way to do it.
I run 2 queries, one to get top 2, then second to get others:
SELECT * FROM table order by Votes desc LIMIT 2
SELECT * FROM table order by Id desc
And then in PHP i make sure that i show 1st query as it is, and on displaying 2nd query i remove entry's that are in 1st query so they don't double.
Can this be done in single query to select first two top voted, then others?
You would have to use subqueries or union - meaning you have a single outer query, which contains multiple queries inside. I would simply retrieve the IDs from the first query and add a id not in (...) criterion to the where clause of the 2nd query - thus filtering out the posts retrieved in the first query:
SELECT * FROM table WHERE Id NOT IN (...) ORDER BY Id DESC
With union the query would look like as follows:
(SELECT table.*, 1 as o FROM table order by Votes desc LIMIT 2)
UNION
(SELECT table.*, 0 FROM table
WHERE Id NOT IN (SELECT Id FROM table order by Votes desc LIMIT 2))
ORDER BY o DESC, if(o=1,Votes,Id) DESC
As you can see, it wraps 3 queries into one and has a more complicated ordering as well because in union the order of the records retrieved is not guaranteed.
Two simple queries seem to be a lot more efficient to me in this particular case.
There could be different ways to write a query that returns the rows in the order you want. My solution is this:
select
table.*
from
table left join (select id from table order by votes desc limit 2) l
on table.id = l.id
order by
case when l.id is not null then votes end desc,
tp.id
the subquery will return the first two id ordered by votes desc, the join will succeed whenever the row is one of the first two otherwise l.id will be null instead.
The order by will order by number of votes desc whenever the row is the first or the second (=l.id is not null), when l.id is null it will put the rows at the bottom and order by id instead.
Is there a way to do a query that orders by a field after a certain element id. I am trying to implement pagination based on the last returned element, and want to be able to both order elements a property and return the next paged based on the last element of the previous page.
For example a user may ask for 25 elements after element with id = 10 sorted on cost.
Imagine you have:
id | name | price
1 | Fish | 5
2 | Burger | 2
3 | Veggies | 6
If we want to get after id=2 sorted by price it should return
2 | Burger | 2
1 | Fish | 5
3 | Veggies | 6
If we want to get after id=1 sorted by price it should return
1 | Fish | 5
3 | Veggies | 6
You can do:
SELECT *
FROM YOURTABLE
WHERE id >= 10
ORDER BY cost ASC
LIMIT 25;
EDIT:
According to your new information, you can do that with:
SELECT *
FROM YOURTABLE
WHERE price >= (SELECT price from Table1 WHERE id = 2)
ORDER BY price ASC
LIMIT 25;
sql fiddle demo
I'm building a little quiz game in PHP/MySQL. After asking questions I want a screen to display how many of the last round were answered correctly.
Im storing whether they were answered correctly or not in a table that looks like this:
rowID | questionid | playerid | answercorrect |
1 | 1 | 1 | 1 |
2 | 2 | 1 | 1 |
3 | 3 | 1 | 1 |
4 | 4 | 1 | 1 |
5 | 5 | 1 | 0 |
6 | 6 | 1 | 1 |
7 | 7 | 1 | 1 |
I want to see how many of the last x (usually 5) questions were answered correctly.
I thought this would be simple. I'm trying this:
SELECT sum( answercorrect ) FROM `answersgiven` ORDER BY id DESC LIMIT 5
I thought this would sum the answercorrect column for the last 5 rows, giving me an answer of 4, but it's giving me 7, which is the result for ALL of the rows.
I feel like I'm missing something obvious. It seems like a simple thing to want to do.
Any ideas?
Try this:
SELECT sum(answercorrect)
FROM (SELECT answercorrect FROM `answersgiven` ORDER BY rowID DESC LIMIT 5) t1
Example Fiddle
In your query, the LIMIT clause affects the overall result: So first all are summed up (which results in one row - the sum over all rows) and then the first 5, if available, are taken (which again is just the one row).
The easiest way of achieving your target is to first select just the first 5 rows (in the subselect) and then sum up afterwards.
try this query
SELECT sum(col)
FROM (SELECT col FROM `table` ORDER BY id DESC LIMIT 5) t1
You're almost there. Just sum up those top 5 answers now:
SELECT SUM('top5')
FROM
(SELECT answercorrect AS 'top5'
FROM `answersgiven`
ORDER BY id DESC LIMIT 5) 'x'