How to check a comma separated value contains another array in linq

The trick here is to use the Intersect method to select the matching values in the 2 string arrays.Then use Count() to check if there's a match with the same count as orderCostCenter.

var orderCostCenter = orderDetails.Select(c => c.CostCenterId);
var listProcess = process.Where(c => c.companyID == 1 &&
  c.CostCenter.Split(',').Intersect(orderCostCenter).Count() == orderCostCenter.Count());

Quote:

i need this output using linq :
{Id=1, Name="Process 01", CostCenter="1,2,3,4" , companyID = 1 },
{Id=3, Name="Process 03", CostCenter="1,2,5" , companyID = 1 },

void Main()
{

	List<Process > process= new List<Process >()
	{
		new Process{Id=1, Name="Process 01", CostCenter="1,2,3,4" , companyID = 1  },
		new Process{Id=2, Name="Process 02", CostCenter="1,4,10"  , companyID = 1  },
		new Process{Id=3, Name="Process 03", CostCenter="1,2,5"   , companyID = 1  },
	};
	
	List<orderDetails> orderDetails= new List<orderDetails>()
	{
		new orderDetails{ Id=1, Name="order 01", CostCenterId ="1" , companyID = 1},
		new orderDetails { Id=2, Name="order 02", CostCenterId="2" , companyID = 1},
	};

	var result = process
		.Where(x=> x.CostCenter.Contains(string.Join(",", orderDetails.Select(o=> o.CostCenterId))))
		.ToList();
	foreach(var r in result)
		Console.WriteLine($"Id={r.Id}\tName='{r.Name}'\tCostCenter='{r.CostCenter}'\tcompanyID={r.companyID}");
}

// Define other methods and classes here
public class Process
{
	public int Id;
	public string Name;
	public string CostCenter;
	public int companyID;
}

public class orderDetails
{
	public int Id;
	public string Name;
	public string CostCenterId;
	public int companyID;
}

Id=1  Name='Process 01'  CostCenter='1,2,3,4'  companyID=1
Id=3  Name='Process 03'  CostCenter='1,2,5'  companyID=1

var finalList = new List();
            process.ForEach(y =>
            {
                var vardata = orderDetails.Select(x => x.CostCenterId).ToArray();
                var data1 = y.CostCenter.Split(',').Intersect(vardata);
                if (data1.ToArray().SequenceEqual(vardata))
                {
                    finalList.Add(y);
                }                
            });