How to Correctly Join Three Tables in MySQL Using LEFT JOIN to Retrieve All Persons and Their Associated Fears?

Multiple Table Joining with MySQL LEFT JOIN

In this scenario, we encounter a challenge of joining three tables: 'Persons', 'Fears', and 'Person_Fear'. The objective is to display all records from the 'Persons' table along with any associated fears, even if some persons have no fears.

Initially, the provided LEFT JOIN query attempts to join 'Person_Fear.PersonID' with 'Person_Fear.FearID', which yields incorrect results. The correct approach is to join 'Person_Fear' with 'Persons' and 'Fears' based on the proper foreign key relationships.

Solution:

SELECT Persons.Name, Persons.SS, Fears.Fear 
FROM Persons
LEFT JOIN Person_Fear ON Person_Fear.PersonID = Persons.PersonID
LEFT JOIN Fears ON Person_Fear.FearID = Fears.FearID

This revised query effectively joins 'Persons' onto 'Person_Fear' and 'Fears' via their respective foreign keys. The LEFT JOIN between 'Persons' and 'Person_Fear' ensures that all records from the 'Persons' table are included, regardless of whether they have any associated fears.

Alternative Solution:

SELECT Persons.Name, Persons.SS, Fears.Fear 
FROM Persons
LEFT JOIN Person_Fear 
    INNER JOIN Fears ON Person_Fear.FearID = Fears.FearID
ON Person_Fear.PersonID = Persons.PersonID

This alternative approach utilizes an INNER JOIN between 'Person_Fear' and 'Fears' to filter down to the relevant fears. The subsequent LEFT JOIN with 'Persons' still ensures that all individuals are included in the results.

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