[nhusers] LINQ gerenrating a 'or' when I user '==' operator

[Jean Bastos]

When I do this query:

var query = from entity in session.Query<Entity>()
where entity.Status != 2
select entity;

NHibernate generate this SQL:

SELECT ...
FROM TABLE_NAME ALIAS
WHERE ALIAS.SITFIL <> 2
or ALIAS.SITFIL is null /*this 'or' is the problem*/

Why NHibernate do this?

The 'or' causes a performance issue on my application I want to generate
just:

SELECT ...
FROM TABLE_NAME ALIAS
WHERE ALIAS.SITFIL <> 2

Without 'Or field is null'

The mapping not is nullable:

[Property(Column = "SITFIL")]public virtual TypeEnumOfProperty Status { get; set; }

The enum:

public enum TypeEnumOfProperty{
[Display(Name = "Ativa", Description ="Ativo")]
Ativa = 0,
[Display(Name = "Inativa", Description = "Inativo")]
Inativa = 1,
[Display(Name = "Inativa e oculta", Description = "Inativo e oculto")]
InativaOculta = 2,}

If I change the TypeEnumOfProperty to int the SQL is generated like I want,
if change to TypeEnumOfProperty or long then was generated with the 'or'

Someone knows why and how solve this?

[Ricardo Peres]

Have you tried setting NotNull = true in the [Property]?
If you think about it, it makes sense: if you want the column to have a value different than X, an option is for it to be null. And because you are using attributes to map your classes, you need to tell NHibernate exactly what you want.

RP

[Jean Bastos]

Yes, I did.
I put NotNull = true in the [Property], but don't makes diference.

Post by Ricardo Peres
Have you tried setting NotNull = true in the [Property]?
If you think about it, it makes sense: if you want the column to have a
value different than X, an option is for it to be null. And because you are
using attributes to map your classes, you need to tell NHibernate exactly
what you want.
RP
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[Ricardo Peres]

OK, so it seems NHibernate is ignoring it.
But, to be fair, other than skipping the null check, the query does make
sense because if you want a value to be different than something, it can
also be null. The syntax for null is different and if you compare something
with null using either = or <>, you always get false.

RP