Question

How can I convert the following SQL queries into LINQ query form in C#, .NET 3.5 code:
1)

select COUNT(distinct Skill_Name) 
from Table1  
where Department = 'ABC' and  Skill_Name is not null 

2)

select distinct location, country from Customer where  Customer_Code ='1001';

Answer 1

I suspect you want:

var query = from entry in dbContext.Table1
            where entry.Department == "ABC" && entry.SkillName != null
            select entry.SkillName;

var count = query.Distinct().Count();

Or using extension method syntax, in one go:

var count = dbContext.Table1
                     .Where(entry => entry.Department == "ABC" && 
                                     entry.SkillName != null)
                     .Select(entry => entry.SkillName)
                     .Distinct()
                     .Count();

As shown by mesiesta, you can combine query expressions with calls not supported within query expressions, but I tend to assign the query expression to an intermediate variable… I personally find it clearer, but use whichever you (and your team) prefer.