MySQL子句在什么情况下

Question

I am trying to figure it out but no solution at all. My query :

SELECT * FROM table
WHERE owner = 'user'
AND (
    CASE WHEN status = 'NEW'
    THEN status = 'NEW'
    ELSE status IN ('CB','NA','NI','GC','FC')
    END
)
ORDER BY RAND() DESC
LIMIT 1;

What I want to achieve is to show all records where status is NEW in an Random order limited by one row each, when no records NEW for the user the query needs to show the other statuses .

Thank you.

Answer 1

SELECT * FROM Table
WHERE owner = 'user'
AND (CASE WHEN (SELECT COUNT(*) FROM Table WHERE status = 'NEW') >= 1 THEN
                status = 'NEW'
     ELSE status IN ('CB','NA','NI','GC','FC')
     END)
ORDER BY RAND() DESC
LIMIT 1;

Demo

http://sqlfiddle.com/#!9/09b1c8/1

Answer 2

What i think, you can simply

SELECT * FROM table
WHERE owner = 'user'
AND (
   CASE WHEN status = 'NEW'
   THEN status = 'NEW'
   ELSE status IN ('CB','NA','NI','GC','FC')
   END
)
ORDER BY RAND() DESC
LIMIT 1;

To

SELECT * FROM table
WHERE owner = 'user' AND status IN ('NEW','CB','NA','NI','GC','FC')
GROUP By some_id
ORDER BY RAND() DESC
LIMIT 1;

Answer 3

SELECT * FROM table
    WHERE owner = 'user'
      AND status IN ('NEW', 'CB','NA','NI','GC','FC')
    ORDER BY status = 'NEW' DESC,
             RAND() DESC
LIMIT 1;

Will give you a total of 1 row, giving preference to a random 'NEW'. If no 'NEW' rows, then a random one of the others.

(Please clarify your Question and provide sample output.)