How to return NULL in LEFT JOIN?

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I have two tables I need to manipulate:

  • interventioniscy : idintervencaopriority , idcelula...

  • cellula : idcelula, name...

    SELECT ip.idintervencaoprioridade, zc.nome nome_celula 
FROM intervencaoprioridade ip 
LEFT JOIN celula zc ON ip.idcelula = zc.idcelula 
WHERE ip.idintervencaoprioridade = 22

The field ip.idcelula can be NULL, but when I do this query returns the first record of the table celula. I’ve seen other examples in ONLY, but I saw nothing to help me.

sql

  • There’s something strange here. You want to do it. left join of the entity celula and you’re wearing a zonacelula

  • fixed, and it already works, I was making a WHERE for an id that was not null. happens.

1 answer

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This can happen to more users as in my case, I leave my answer and solution if it is useful to others.

When I auditioned for a id = 22 this one didn’t have the field idcelula to null hence he returns another value which by coincidence was the first. Taking the test more carefully I noticed that detail, and I changed the test log to one that had the idcelula to null.

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