public void TestConditionOperator()

{

    // Conditional Operator: ? :

    bool isUsa = true;

    SqlParameter param = new SqlParameter();

    // Problem: 'System.DBNull' and 'string' (“USA“) are different object types. 

    param.Value = isUsa ? DBNull.Value : "USA";

    // The above line of code generates the following error: 

    // Type of conditional expression can't be determined because there is no implicit 

    // conversion between 'System.DBNull' and 'string'

    // Solution: Cast each object to an object data type.

    param.Value = isUsa ? DBNull.Value as object: "USA" as object;

}