[mysql] MySQL Multiple Joins in one query?

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?

This question is related to mysql sql join

The answer is


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

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/


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")


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