Question

I have the following query:

SELECT 
  IF(COUNT(*) > 0, COUNT(*), '0') AS Found, 
  IF(NWLat, NWLat, '0')           AS NWLat, 
  IF(NWLon, NWLon, '0')           AS NWLon, 
  IF(SELat, SELat, '0')           AS SELat, 
  IF(SELon, SELon, '0')           AS SELon 
FROM s 
WHERE s.ci = '4' 
  AND s.snf = 'Ch'
GROUP BY s.sid 

Right now it returns rows for matched query. However, when nothing is matched, it returns nothing. How can I make it return “Found: 0, NWLat: 0, NWLon: 0, SELat: 0, SELon: 0” if nothing is found?

Answer 1

It is better, not to do so in MySQL. SQL is not about that. From your front end application if your query doesn’t return any records, then you can easily print 0’s.

However, if you need to do this any way you can do this:

SELECT 
  IF(COUNT(*) > 0, COUNT(*), '0') AS Found, 
  IF(NWLat, NWLat, '0')           AS NWLat, 
  IF(NWLon, NWLon, '0')           AS NWLon, 
  IF(SELat, SELat, '0')           AS SELat, 
  IF(SELon, SELon, '0')           AS SELon 
FROM s 
WHERE s.ci = '4' 
  AND s.snf = 'Ch'
GROUP BY s.sid 
UNION ALL
SELECT
  '0' AS Found, 
  '0' AS NWLat, 
  '0' AS NWLon, 
  '0' AS SELat, 
  '0' AS SELon 
FROM s 
WHERE NOT EXISTS(
    SELECT 
      IF(COUNT(*) > 0, COUNT(*), '0') AS Found, 
      IF(NWLat, NWLat, '0')           AS NWLat, 
      IF(NWLon, NWLon, '0')           AS NWLon, 
      IF(SELat, SELat, '0')           AS SELat, 
      IF(SELon, SELon, '0')           AS SELon 
    FROM s 
    WHERE s.ci = '4' 
    AND s.snf = 'Ch'
    GROUP BY s.sid
);

Demos:

• If there is records.

• IF there is no records returned, and this will give you:

  | FOUND | NWLAT | NWLON | SELAT | SELON |
  -----------------------------------------
  |     0 |     0 |     0 |     0 |     0 |