使用 IN 运算符并在 LINQ C# 中获取不同的值

Question

I have the below SQL query, Which I need to convert to LINQ. The SQL query:

select distinct a.DeliverableAdditionalFieldId, b.FieldName, b.CustomFieldType
from PrefixDeliverableAdditionalFieldsMapping as a, DeliverableAdditionalField as b
where a.DeliverableAdditionalFieldId = b.Id
and b.IsActive = 1
and a.PrefixId in (184,183)

I converted the sql query to LINQ which is below:

var prefixIds = "184, 183"

from prefix in context.PrefixDeliverableAdditionalFieldsMappings
join additionalField in context.DeliverableAdditionalFields on prefix.DeliverableAdditionalFieldId equals additionalField.Id
where additionalField.IsActive == true && prefixIds.Contains(prefix.PrefixId.ToString())
select new AdditionalCustomField
{
    AdditionalFieldId = prefix.DeliverableAdditionalFieldId,
    AdditionalFieldName = additionalField.FieldName,
    FieldType = additionalField.CustomFieldType

}).Distinct().ToList()

For IN Operator of SQL, in LINQ I used the code: prefixIds.Contains(prefix.PrefixId.ToString(). Now I need to sure that this is OK. Please let me know is there any other alternative way?

And is there any alternate way to use distinct and the way I used, will it work?

Answer 1

You are now doing .Contains() on a string, so eg "1" will also be found, and I'm pretty sure you don't want that to happen.

Instead, define prefixIds as a collection of the desired type, eg int[] :

var prefixIds = new[] { 184, 183 };

And then you can use it as follows:

where ..... && prefixIds.Contains(prefix.PrefixId)

This translates to a SQL IN (...) clause.