/// <summary>
/// static method for comparing two ExpressionElement. This is used in =, <, >, <>, <=, >= elements.
/// If elements are equal returns 0, if E1 is less that E2, return -1 else if E1 is greater 1
/// </summary>
protected static int Compare (ExpressionElement E1, ExpressionElement E2, DataRow Row)
{
ExpressionElementComparer comparer = new ExpressionElementComparer(E1, Row);
return comparer.CompareTo(E2);
}
/// <summary>
/// IsNull function does not return boolean value, so throw exception
/// </summary>
public override bool Test (DataRow Row)
{
ExpressionElement E;
ExpressionElement columnElement = (ExpressionElement)Elements [0];
ExpressionElementComparer comparer = new ExpressionElementComparer(columnElement, Row);
for (int i = 1; i < Elements.Count; i++)
{
E = (ExpressionElement)Elements [i];
if(comparer.CompareTo(E) == 0)
return true;
}
return false;
}
