Question

I am trying to join three tables in MySQ, but when I do it my way, I get duplicate rows with incorrect values. and it appears that I am not doing it correctly.

I have three tables that I need to join:

nt_stentyper
id | tagsten | varenr_tilb | prod_type | dk | no | sv

nt_tunliste
varenummer | tunnummer | beskrivelse 

nt_priser
varenummer | pris

The data I wish to find is grouped by the varenummer in nt_tunliste and nt_priser. That varenummer is taken for varenr_tilb.

I tried this:

SELECT * FROM nt_stentyper 
INNER JOIN nt_tunliste ON nt_stentyper.varenr_tilb = nt_tunliste.varenummer 
INNER JOIN nt_priser ON nt_stentyper.varenr_tilb = nt_tunliste.varenummer 
WHERE nt_stentyper.tagsten = 1 
ORDER BY nt_stentyper.prod_type ASC

… but that gives me duplicate rows like:

ID  tagsten varenr_tilb prod_type   dk  no  sv  varenummer  tunnummer   beskrivelse  varenummer pris_dk
1   1       12345678    1           1   1   1   12345678    12131415    RT 801       11111111   213
1   1       12345678    1           1   1   1   12345678    12131415    RT 801       12345678   200
5   1       11111111    5           1   1   1   11111111    11111112    Gratbånd     11111111   213
5   1       11111111    5           1   1   1   11111111    11111112    Gratbånd     12345678   200

… which isn’t what I want.

The query should only display one varenummer.

Answer 1

the condition on the second join should have something to do with nt_priser, but it’s a duplicate of the first join condition.