Question

I have a loooooooooooong SELECT ending with a ORDER BY that can include the following values :

• checked (1 or 0)
• date (YYYY-MM-DD)
• time (HH:MM:SS)

I’d like to order the result of the query the following way :

|__checked = 0
|            |__ date ASC
|            |__ time ASC
|            |__ date && time are null  
|__checked = 1
             |__ date ASC
             |__ time ASC
             |__ date && time are null  

For now, I got something simple like “ORDER BY i1.checked, date, time” but the trouble is with this the items with empty date and times stay on the top.

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Here is the whole query if you ever think you need all the data to find a proper solution. Don’t scream.

SELECT i1._id AS _id, i1.title AS title, i1.checked AS checked, 

   // count the children (-1 is because the closure table include a relation between any item and itself)   
   (count( c1.item_id )  - 1) AS children_count, 

   // count the unchecked children 
   (SELECT (COUNT(DISTINCT i2._id) ) 
   FROM item AS i2 JOIN closure AS c2 ON (i2._id = c2.item_id) 
   WHERE c2.ancestor_id = i1._id 
   AND i2.checked = 0  
   AND c2.item_id NOT IN (0, i1._id)) AS unchecked_children_count, 

   // get the closest deadlines among the children :
   // if there is a date but no time, time is set to 00:00:00
   // if there is a time but not date, date is set to today
   // if there is no date nor time, both are set to an empty string

   // date
   ifnull(nullif((SELECT ifnull(nullif(i3.date, ""), date()) AS subdate
                  FROM item AS i3 JOIN closure AS c3 ON (i3._id = c3.item_id) 
                  WHERE c3.ancestor_id = i1._id
                  AND (i3.date OR i3.time) 
                  ORDER By subdate, ifnull(nullif(i3.time, ""), "00:00:00") 
                  LIMIT 1), ""), "") AS date, 

   // time           
   ifnull(nullif((SELECT ifnull(nullif(i4.time, ""), "00:00:00") AS subtime
                  FROM item AS i4 JOIN closure AS c4 ON (i4._id = c4.item_id) 
                  WHERE c4.ancestor_id = i1._id 
                  AND (i4.date OR i4.time) 
                  ORDER By ifnull(nullif(i4.date, ""), date()), subtime 
                  LIMIT 1), ""), "") AS time 

FROM item AS i1 JOIN closure AS c1 ON ( i1._id = c1.ancestor_id ) 
WHERE i1.parent_id = 0
AND c1.item_id != 0 

GROUP BY c1.ancestor_id 

ORDER BY i1.checked, date, time

The items are organised in a tree with a parent_id and a closure table.

Answer 1

ORDER BY il.checked, 
         CASE WHEN date IS NULL AND time IS NULL THEN 1 ELSE 0 END, 
         date, time