join three tables for specific result

Question

I have three tables:

Table 1 Users:

+----------+------------+------------+-------------------+
| ID [PK]  |  username  |           


        

Answer 1

A LEFT JOIN will always return all records from the table on the left of the join, and only values from those records which match the join criteria from tables on the right of the join.

To only return records for which there join criteria is validated for every record, you should use an INNER JOIN, i.e.:

SELECT * 
FROM 
    CR_AR C 
    INNER JOIN STRUCT S ON S.STRUCTURE = C.STRUCT 
    INNER JOIN USERS U ON U.USER_STRUCT = S.STRUCTURE