Where IN clause in LINQ [duplicate]

How to make a where in clause similar to one in SQL Server?

I made one by myself but can anyone please improve this?

    public List<State> Wherein(string listofcountrycodes)
    {
        string[] countrycode = null;
        countrycode = listofcountrycodes.Split(',');
        List<State> statelist = new List<State>();

        for (int i = 0; i < countrycode.Length; i++)
        {
            _states.AddRange(
                 from states in _objdatasources.StateList()
                 where states.CountryCode == countrycode[i].ToString()
                 select new State
                 {
                    StateName  = states.StateName                    

                 });
        }
        return _states;
    }

This expression should do what you want to achieve.

dataSource.StateList.Where(s => countryCodes.Contains(s.CountryCode))

This will translate to a where in clause in Linq to SQL...

var myInClause = new string[] {"One", "Two", "Three"};

var results = from x in MyTable
              where myInClause.Contains(x.SomeColumn)
              select x;
// OR
var results = MyTable.Where(x => myInClause.Contains(x.SomeColumn));

In the case of your query, you could do something like this...

var results = from states in _objectdatasource.StateList()
              where listofcountrycodes.Contains(states.CountryCode)
              select new State
              {
                  StateName = states.StateName
              };
// OR
var results = _objectdatasource.StateList()
                  .Where(s => listofcountrycodes.Contains(s.CountryCode))
                  .Select(s => new State { StateName = s.StateName});

I like it as an extension method:

public static bool In<T>(this T source, params T[] list)
{
    return list.Contains(source);
}

Now you call:

var states = _objdatasources.StateList().Where(s => s.In(countrycodes));

You can pass individual values too:

var states = tooManyStates.Where(s => s.In("x", "y", "z"));

Feels more natural and closer to sql.

public List<Requirement> listInquiryLogged()
{
    using (DataClassesDataContext dt = new DataClassesDataContext(System.Configuration.ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString))
    {
        var inq = new int[] {1683,1684,1685,1686,1687,1688,1688,1689,1690,1691,1692,1693};
        var result = from Q in dt.Requirements
                     where inq.Contains(Q.ID)
                     orderby Q.Description
                     select Q;

        return result.ToList<Requirement>();
    }
}

Where IN clause in LINQ [duplicate]

Related

Recent Posts