无法检查所有记录是否在字段中都有特定值

Question

I'm trying to check if a specific list of matches have as status: 3 and 5, so suppose I have a list of matches like this:

id | round_id | status 
 1      28        3
 2      28        3 
 3      28        5
 4      28        5

the query result should return true because all the matches available have as status 3 or 5 . I wrote this query:

SELECT (SELECT COUNT(DISTINCT `status`) FROM `match` WHERE round_id = 28 AND (`status` = 3 OR`status` = 5)) = 1 AS result

but this will return 0

Answer 1

You can do:

select ( count(*) = sum(status in (3, 5)) ) as flag_3_5
from matches
where round_id = 28;

You can do this for all rounds by using group by round_id .

MySQL treats boolean expressions as numbers in a numeric context, with true being "1" and false being "0". So, sum(status in (3, 5)) counts the number of rows with these two statuses. The comparison checks to see if these are all rows.

Answer 2

You can use exists :

select distinct m.round_id, (case when exists (select 1 
                                               from match m1 
                                               where m1.round_id = m.round_id and 
                                                     m1.status in (3,5)
                                               ) 
                                  then 'true' else 'false' 
                             end) as result
from match m
where round_id = 28;

Answer 3

Try this:

select round_id from matches
where status in (3, 5)
group by round_id
having count(distinct status) > 1