MYSQL Inner Join if statement

Question

i\'m trying to join 3 tables together but use an IF statment to only run a certain query

I have a user table, customer and staff table. The first part below works:

Answer 1

Doesn't this works?

INNER JOIN `staff` ON `user`.userID = staff.userID AND user.level = 2
INNER JOIN `customer` ON user.userID = customer.userID AND user.level = 1