how to use sql join in mysql

Question

table name: tbl_schedule

tr_id(P.K.)  mr_id(F.K.)   sch_date   doctor_id   
-----------  -----------   --------   ----------
1              23         01/01/2012         


        

Answer 1

You can try this

SELECT b.mr_id, b.mr_fname, b.mr_lname, 
     (SELECT COUNT(*) FROM tbl_schedule a WHERE (a.my_id = b.my_id)
     AND (Date >= '2012-04-01') AND (Date <= '2012-04-20')) AS COUNT
FROM tbl_user

You do not need to INNER JOIN, because it seems like you want to include ALL of the users in the tbl_users table.

Edit: You added later that you do not want a count of 0

SELECT b.mr_id, b.mr_fname, b.mr_lname, COUNT(*)
FROM tbl_schedule a 
INNER JOIN tbl_users b ON a.tr_id = b.mr_id
WHERE (Date >= '2012-04-01') AND (Date <= '2012-04-20')
GROUP BY b.mr_id, b.mr_fname, b.mr_lname