使用内连接和4个表是可能的

Question

i have a members table that contain 3 field as a foreign key for 3 tables

so i want to join between them is that possible ??

member table :

• governorate
• district
• village

each field is the foreign key for a table

governorate table :

• governorate_id
• governorat_name

district table :

• district_id
• district_name

village table :

• id
• village_name

can i do it in one query ????

Answer 1

Yes you can.

SELECT  b.governorat_name,
        c.district_name,
        d.village_name
FROM    member a
        INNER JOIN governorate b
            ON a.governorate = b.governorate_id
        INNER JOIN district c
            ON a.district = c.district_id
        INNER JOIN village d
            ON a.village = d.id

To further gain more knowledge about joins, kindly visit the link below:

• Visual Representation of SQL Joins

The query uses INNER JOIN in which results should have atleast one matching record on every parent table ( governorate , district , village ).

When columns are nullable and you want to show all records on table member table whether it has no matching record on the parent table, use LEFT JOIN instead if INNER JOIN .