Traversing a IEnumerable or an Array or a Dataset

One way of doing

var _mipUserVoCol = from _mipUserVOSingle in _mipUserVOCollection
                         where _mipUserVOSingle.UserName ==      Request.QueryString["UserName"].ToString()
                                        select _mipUserVOSingle;

Second way of doing - simple

       
MIPUsersVO _simpleCol = _mipUserVOCollection.Where(n => n.UserName == Request.QueryString["UserName"].ToString()).First();
Assign2Textboxes(_simpleCol);

Comparing two DataSet using LInq

public void CompareActiveDirUsersWithDB()
{

DataSet _dataSetDbUsers=DataManager.GetUsersFromDB();
DataSet _activeDirUsers = ActiveDirectoryUsers();

IEnumerable _dataRowDbUsers = from _datarow in _dataSetDbUsers.Tables[0].AsEnumerable()
where _datarow.Field("UserName") != ""
select _datarow;

IEnumerable _dataRowActiveDirectory = from _dataRow in _activeDirUsers.Tables[0].AsEnumerable()
where _dataRow.Field("UserName") != ""
select _dataRow;

IEnumerable _dbUserNames = _dataRowDbUsers.AsEnumerable().Select(row => (string)row["UserName"]);
IEnumerable _activeDirUserName = _dataRowActiveDirectory.AsEnumerable().Select(row => (string)row["UserName"]);

IEnumerable _usersNotInDB = _activeDirUserName.Except(_dbUserNames);
IEnumerable _usersNotInActiveDir = _dbUserNames.Except(_activeDirUserName);
IEnumerable _usersInDB = _activeDirUserName.Intersect(_dbUserNames);


}

taking the data from two different Ilist or list

var q = (from _tblUser in _tblUserDAO
join EmpType in _tblEmpTypeVOList on _tblUser.EmployeetypeIDFK equals EmpType.EmployeeTypeID
select new
{
UserName = string.IsNullOrEmpty(_tblUser.UserName) ? "N/A" : _tblUser.UserName,
FirstName = _tblUser.FirstName,
LastName = _tblUser.LastName,
Email = _tblUser.Email,
Phone = _tblUser.Phone,
Status = _tblUser.IsActive == 1 ? "Active" : "Inactive",
EmployeeTypeName = EmpType.EmployeeTypeName.ToLower() == "attorney" ? "A" : "I"
});



return q.ToList();