public ExprNode(RelNode lr, string op, RelNode rr) : base(NodeType.ExprNode)
{
l_relation = lr;
r_relation = rr;
this.op = op;
children = new List <BaseNode>();
children.Add(l_relation);
children.Add(r_relation);
}
public ExprNode(RelNode lr) : this(lr, null, null)
{
}
