Where IN clause in LINQ
C#LinqC# Problem Overview
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;
}
C# Solutions
Solution 1 - C#
This expression should do what you want to achieve.
dataSource.StateList.Where(s => countryCodes.Contains(s.CountryCode))
Solution 2 - C#
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});
Solution 3 - C#
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.
Solution 4 - C#
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>();
}
}
Solution 5 - C#
The "IN" clause is built into linq via the .Contains() method.
For example, to get all People whose .States's are "NY" or "FL":
using (DataContext dc = new DataContext("connectionstring"))
{
List<string> states = new List<string>(){"NY", "FL"};
List<Person> list = (from p in dc.GetTable<Person>() where states.Contains(p.State) select p).ToList();
}
Solution 6 - C#
from state in _objedatasource.StateList()
where listofcountrycodes.Contains(state.CountryCode)
select state
Solution 7 - C#
This little bit different idea. But it will useful to you. I have used sub query to inside the linq main query.
Problem:
Let say we have document table. Schema as follows schema : document(name,version,auther,modifieddate) composite Keys : name,version
So we need to get latest versions of all documents.
soloution
var result = (from t in Context.document
where ((from tt in Context.document where t.Name == tt.Name
orderby tt.Version descending select new {Vesion=tt.Version}).FirstOrDefault()).Vesion.Contains(t.Version)
select t).ToList();
Solution 8 - C#
public List<State> GetcountryCodeStates(List<string> countryCodes)
{
List<State> states = new List<State>();
states = (from a in _objdatasources.StateList.AsEnumerable()
where countryCodes.Any(c => c.Contains(a.CountryCode))
select a).ToList();
return states;
}