MySQL Multiple Joins in one query

Question

I have the following query   SELECT   dashboard data headline    dashboard data message    dashboard messages image id  FROM dashboard data INNER JOIN dashboard messages   ON dashboard message id   dashboard messages id   So I am using an INNER JOIN and grabbing the image id   So now  I want to take that image id and turn it into images filename from the images table    How can I add that in to my query

User · Answer

Multi joins in SQL work by progressively creating derived tables one after the other. See this link explaining the process:

https://www.interfacett.com/blogs/multiple-joins-work-just-like-single-joins/

User · Answer

Just add another join   SELECT dashboard data headline         dashboard data message         dashboard messages image id         images filename  FROM dashboard data      INNER JOIN dashboard messages             ON dashboard message id   dashboard messages id      INNER JOIN images             ON dashboard messages image id   images image id

User · Answer

You can simply add another join like this   SELECT dashboard data headline  dashboard data message  dashboard messages image id  images filename FROM dashboard data      INNER JOIN dashboard messages          ON dashboard message id   dashboard messages id     INNER JOIN images         ON dashboard messages image id   images image id    However be aware that  because it is an INNER JOIN  if you have a message without an image  the entire row will be skipped  If this is a possibility  you may want to do a LEFT OUTER JOIN which will return all your dashboard messages and an image filename only if one exists  otherwise you ll get a null   SELECT dashboard data headline  dashboard data message  dashboard messages image id  images filename FROM dashboard data      INNER JOIN dashboard messages          ON dashboard message id   dashboard messages id     LEFT OUTER JOIN images         ON dashboard messages image id   images image id

User · Answer

I shared my experience of using two LEFT JOINS in a single SQL query   I have 3 tables   Table 1  Patient consists columns PatientID  PatientName  Table 2  Appointment consists columns AppointmentID  AppointmentDateTime  PatientID  DoctorID  Table 3  Doctor consists columns DoctorID  DoctorName    Query   SELECT Patient patientname  AppointmentDateTime  Doctor doctorname  FROM Appointment   LEFT JOIN Doctor ON Appointment doctorid   Doctor doctorId    have doctorId column common  LEFT JOIN Patient ON Appointment PatientId   Patient PatientId        have patientid column common  WHERE Doctor Doctorname LIKE  varun      setting doctor name by using LIKE  AND Appointment AppointmentDateTime BETWEEN  1 16 2001  AND  9 9 2014    comparison b w dates   ORDER BY AppointmentDateTime ASC      getting data as ascending order     I wrote the solution to get date format like  mm dd yy   under my name  VARUN TEJ REDDY

[mysql] MySQL Multiple Joins in one query?

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