Question

So, I’m completely new to mySql and just trying to self teach it.

Example table structure:

tblA
-----
PK: userId

tblB
-----
PK: workoutId
FK: userId

tblC
-----
PK: cardioId
FK: workoutID

table C has a distance field.

Currently when I run SELECT SUM(distance) FROM tblC I get the correct amount, however, when I only want to select the sum of distance for the particular user, I tried:

SELECT SUM(distance) FROM tblC JOIN tblB ON (tblC.workoutId AND tblB.workoutId) WHERE userId = '1'

This gives a me a rediculously higher value than before. Where am I going wrong?

Answer 1

SELECT SUM(distance)
FROM tblC
JOIN tblB ON tblC.workoutId = tblB.workoutId
         AND tblB.userOd = 1