MySQL COUNT() GROUP BY doesn't work

Question

I have a problem in counting by MySQL in a GROUP BY This is the query that does not return the desired result.

SELECT COUNT(bagno)
FROM disposizione_assegnazione_pezze
JOIN pezze 
  ON pezza = id
WHERE id_prodotto_tessuto = 12096
  AND id_collezione = 11 
  AND id_stagione = 22 
  AND id_tema = 1
GROUP BY bagno

The result of the count is 3

This is the pezza table and its primary key is id

This is the table disposizione_assegnazione_pezze that has the pezza column which refers to the previous table

Why does not return 1 as a result my query?

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Question of the problem

I want to count how many different bagno are there

Answer 1

I dont think you need GROUP BY, instead use DISTINCT

 SELECT COUNT(DISTINCT bagno)

SQL DEMO

Check your query without agregatted function COUNT/GROUP BY

As you can see bagno = 55 appear three times, that is why when you group by bagno and count get 3.