MySQL Query two different conditions for different count in 1 query

问题

I have 3 tables named

com_event_schedules
com_appointments
com_event_schedules_com_appointment_c

which has a relation between first two tables.

Following are the fields of the tables

com_event_schedules -- id -- name -- schedule_date -- start_time -- end_time -- deleted
com_appointments -- id -- start_time -- end_time -- status
com_event_schedules_com_appointment_c -- id -- com_event_schedules_com_appointmentcom_event_schedules_ida (schedule_id) -- com_event_schedules_com_appointmentcom_appointment_idb (appointment_id)

relation between tables com_event_schedule and com_appointments is 1 to Many

What I want result having schedule_id, and total counts of its appointments on condition status='completed'

I tried following query:

SELECT sch.id,COUNT(app.id) AS total,
  (SELECT COUNT(ap.id) 
  FROM 
  com_appointment ap, 
  com_event_schedules sc, 
  com_event_schedules_com_appointment_c re 
  WHERE 
  re.com_event_schedules_com_appointmentcom_event_schedules_ida=sc.id AND  
  ap.id=re.com_event_schedules_com_appointmentcom_appointment_idb AND 
  sc.deleted=0 AND 
  ap.status='completed') AS completed

FROM 
com_event_schedules sch,
com_appointment app,
com_event_schedules_com_appointment_c rel 
WHERE 
rel.com_event_schedules_com_appointmentcom_event_schedules_ida=sch.id AND
app.id=rel.com_event_schedules_com_appointmentcom_appointment_idb AND 
sch.deleted=0 GROUP BY sch.id

Using this query Im getting accurate total count but completed count is not as expected. it is showing 1 for each schedule. However only 1 appointment in db is completed and others are still pending.

Is there something wrong with query ?? I have SugarCRM in backend. Cant use fiddle cause relation and fields are too messy.

回答1:

This query should be able to help you. The biggest thing it does is count ALL of the appointments for total and then SUM on an IF status = completed to get you both the total and the completed in the same query.

SELECT
    sc.id,
    COUNT(ap.id) as total,
    SUM(IF(status = 'completed', 1, 0)) as completed
FROM
    com_event_schedules sc
LEFT JOIN
    com_event_schedules_com_appointment_c re
    ON re.com_event_schedules_com_appointmentcom_event_schedules_ida = sc.id
LEFT JOIN
    com_appointment ap
    ON re.com_event_schedules_com_appointmentcom_appointment_idb = ap.id
WHERE
    sc.deleted = 0
GROUP BY
    sc.id

Also, I was noticing you said that it was a One to Many relationship. Relational tables like you have are really for Many to Many. The most efficient way to have a One to Many is to get rid of the com_event_schedules_com_appointment_c table and add a com_event_schedule_id to the com_appointments table.

来源：https://stackoverflow.com/questions/16977690/mysql-query-two-different-conditions-for-different-count-in-1-query

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