在SELECT中使用时，CASE'NOT NULL'的mysql语法

Question

I am trying to use CASE 'NOT NULL' within a SELECT statement but I keeping getting this error message:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax

SELECT 
        u.id,
                CASE  ph.thumbsize WHEN NULL THEN ph.thumbsize ELSE 'defaultpicture.jpg'

            FROM
            user u  
            LEFT OUTER JOIN
                list_photos ph
        ON 
                u.id = ph.userId;

I have also tried these different formats for CASE :

(CASE WHEN ph.thumbsize IS NOT NULL THEN 'ph.thumbsize' ELSE
 'defaultpicture.jpg')as picture       

           CASE WHEN ph.thumbsize IS NOT NULL THEN ph.thumbsize ELSE defaultpicture.jpg

Answer 1

You're missing an END , among other minor issues. Try:

SELECT 
    u.id,
    CASE WHEN (ph.thumbsize IS NULL) THEN 
        'defaultpicture.jpg'
    ELSE
        ph.thumbsize
    END AS picture
FROM
    user u  
LEFT OUTER JOIN
    list_photos ph
ON 
    u.id = ph.userId;

Answer 2

try this:

SELECT 
    u.id,
            CASE  ph.thumbsize WHEN NULL THEN ph.thumbsize ELSE 'defaultpicture.jpg' END

        FROM
        user u  
        LEFT OUTER JOIN
            list_photos ph
    ON 
            u.id = ph.userId;

In CASE you need to close it by END

Answer 3

Why not using IFNULL :

..., IFNULL(ph.thumbsize,'defaultpicture.jpg') AS picture, ...