[Mariadb] SUM이 null 일 때 0 처리

사용 전

SELECT
    sum(value) AS value_count
FROM tables;

 

사용 후

SELECT
    COALESCE(sum(value),0) AS value_count
FROM tables;

 

++ 추가 case문

SELECT 
    COALESCE(sum(CASE TYPE WHEN 1 THEN CNT else 0 end), 0) As 'value_count1',
    COALESCE(sum(CASE TYPE WHEN 2 THEN CNT else 0 end), 0) AS 'value_count2',
    COALESCE(sum(CASE TYPE WHEN 3 THEN CNT else 0 end), 0) AS 'value_count3'
FROM tables;