MySQL'大于（>）'查询始终返回0

Question

I am working with a query where I want to display number of upcoming dates. The following query returns 0 even though there are dates greater than current date. Please help me to solve this problem.

SELECT  (case when b.booked_date > cast(now() as date) then sum(1) else sum(0) end) as upcoming_booked_facilities                           
        from    svk_apt_book_facilities b   
        where   b.customer_id = 1
                and b.association_id = 1        
                and b.is_active = 1
        group   by b.facility_id

Answer 1

You need to sum a CASE expression to do conditional aggregation:

SELECT
    facility_id,
    SUM(CASE WHEN booked_date > CURDATE() THEN 1 ELSE 0 END) AS upcoming_booked_facilities
FROM svk_apt_book_facilities  
WHERE
    customer_id = 1    AND
    association_id = 1 AND
    is_active = 1
GROUP BY
    facility_id;

You were trying to use the sum as the predicate of the CASE expression, which is probably not what you want. Note that I am also selecting the facility_id , since you are grouping by that column. If you instead want a conditional sum over the entire table, then don't select or group by facility.