How do I implement a dynamic 'where' clause in LINQ?

Question

I want to have a dynamic where condition.

In the following example:

var opportunites =  from opp in oppDC.Opportunities
                    join org in oppDC.Organizations 
                        on opp.OrganizationID equals org.OrgnizationID
                    where opp.Title.StartsWith(title)
                    select new
                    {
                        opp.OpportunityID,
                        opp.Title,
                        opp.PostedBy,
                        opp.Address1,
                        opp.CreatedDate,
                        org.OrganizationName
                    };

Some times I have Title and sometimes I don't. And also I want to add date in where clause dynamically.

For example, like this SQL:

string whereClause;
string SQL = whereClause == string.Empty ? 
     "Select * from someTable" : "Select * from someTable" + whereclause

Answer 1

I was searching for creating a dynamic where clause in LINQ and came across a very beautifull solution on the web which uses ExpressionBuilder in C#.

I am posting it here since none of the above solution uses this approach. It helped me. Hope it helps you too http://www.codeproject.com/Tips/582450/Build-Where-Clause-Dynamically-in-Linq