Question

i want to get result where a column values are NULL using LINQ Expressions

search.AddCriteria(x => x.LogStatus == 
Inventory.AffStatusToChar((EAffidavitLogStatus)byte.Parse(cmbLog.SelectedValue)));

public void AddCriteria (Expression<Func<T, bool>> criteria) {
        if (_where == null) { _where = w => true; }
        _where = And(criteria);
    }


private Expression<Func<T, bool>> And (Expression<Func<T, bool>> expr) {
        return Expression.Lambda<Func<T, bool>>(Expression.And(
                _where.Body,
                Expression.Invoke(expr, _where.Parameters.Cast<Expression>())
            ), _where.Parameters);
    }

//This below part is use to execute the Linq
//IQueryable<T> result = db.GetTable<T>();
//result = result.Where(_where);

result’s where part is looking like WHERE ([t0].[LogStatus]) = @p5)
see i want IS NULL

I want query like this

SQL query : `select * from xyz where abc is NULL`

but the LINQ expression above is converting to
select * from xyz where abc=NULL which gives a different result.

any one gone through this kind a problem? how can IS NULL in LINQ expression achieve this?

Answer 1

Never mind i figured it myself here is the solution what i did

search.AddCriteria(x => !(x.LogStatus!=null));

this returns query like

WHERE (NOT (UNICODE([t0].[LogStatus]) IS NULL ))

tada!! this is what i expected..