CODEWITHSUNDEEP
mysql
Mono
Mono

Reputation: 57

How to create a query with two joins to the same lookup table

I am hoping someone can point me in the correct direction, I am just an amateur playing with a hobby.

I have 2 tables, first table 'tbl_wheel_diameter' has just 'wheel_diameter' and 'id'

Second table 'tbl_tyres' has 'wheel_diameter_front','wheel_diameter_rear' and 'vehicleId'

I need to write a query that selects the front and rear diameter together. This is something I tried.

SELECT  tbl_wheel_diameter.wheel_diameter_front,tbl_wheel_diameter.wheel_diameter_rear
FROM tbl_tyres
INNER JOIN tbl_wheel_diameter
     ON tbl_wheel_diameter.id = tbl_tyres.wheel_diameter
WHERE tbl_tyres.vehicleId = 2

I have read that I should use left joins but I seem to get confused with how to write them?

Upvotes: 0

Views: 64

Answers (1)

Ralph Ritoch
Ralph Ritoch

Reputation: 3440

Add an alias for the table so you can include the same table twice. Here is an example using an alias of t1 and t2.

SELECT  t1.wheel_diameter,t2.wheel_diameter
FROM tbl_tyres
INNER JOIN tbl_wheel_diameter t1
     ON t1.id = tbl_tyres.wheel_diameter_front
INNER JOIN tbl_wheel_diameter t2
     ON t2.id = tbl_tyres.wheel_diameter_rear
WHERE tbl_tyres.vehicleId = 1

Upvotes: 1

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