Question

In LINQ is it safe to carry out an inequality test on a nullable column without having to convert the nullable type?

In T-SQL you have to use ISNULL().
But in LINQ can I safely do?:

mytable.nullablecol != 1

Answer 1

Yes, it’s safe to do it that way round.

EDIT: Given your comment, the problem is probably that null == -1 has a result of null, not true (in SQL). So you could use a query of:

mytable.nullablecol != 1 || mytable.nullablecol == null

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What becomes trickier is when you want to compare for equality with a value which may be null. You have to cater for that explicitly. For example:

int? x = GetId();
var query = from foo in bar
            where foo.X == x || (foo.X == null && x == null)
            select ...;