mysql create view from multiple tables

Question

I want create view from tabel admin, akademik, dosen and mahasiswa, in this view there are have admin, password and id level columns.

have tried this query, but the result is erorr.

CREATE VIEW view_user AS
    SELECT admin.id_level, admin.username, admin.password, akademik.id_level, akademik.username, 
    akademik.password, dosen.id_level, dosen.username, dosen.password, mahasiswa.id_level, 
    mahasiswa.username, mahasiswa.password
FROM admin a
    INNER JOIN akademik b on (a.id_level=b.id_level) AND (a.username=b.username) AND (a.password=b.password)
    INNER JOIN dosen c on (b.id_level=c.id_level) AND (b.username=c.username) AND (b.password=c.password)
    INNER JOIN mahasiswa d on (c.id_level=d.id_level) AND (c.username=d.username) AND (c.password=d.password)
ORDER BY 1;

I want results like this

How can I do that? Can somebody help me

Answer 1

Since you are doing a Inner JOIN on id_level, user_name and password (generally not advised) you don't have to display these 3 columns from all 4 tables, as your desired output is only 3.

CREATE VIEW view_user AS
    SELECT admin.id_level, admin.username, admin.password
FROM admin a
    INNER JOIN akademik b on (a.id_level=b.id_level) AND (a.username=b.username) AND (a.password=b.password)
    INNER JOIN dosen c on (b.id_level=c.id_level) AND (b.username=c.username) AND (b.password=c.password)
    INNER JOIN mahasiswa d on (c.id_level=d.id_level) AND (c.username=d.username) AND (c.password=d.password)
ORDER BY 1;

Additionally you can remove the order in view creation and do it when querying your view, like this

Select * from view_user order by 1;