public override void Perform(Identifier node)
{
if (node == null)
{
throw new ArgumentNullException("node");
}
base.Perform(node);
if (TailorUtil.IsRownum(node))
{
int limit = 0;
QueryExpression query = GetAncestor <QueryExpression>(null, null);
if (query != null)
{
Expression relational = GetExpressionAncestor(null, query);
if (relational != null)
{
limit = TailorUtil.GetRownumExpressionLimit(relational);
if (limit > 0)
{
bool matched = false;
Expression logical = GetExpressionAncestor(relational, query);
if (logical == null)
{
if (query.Where == relational)
{
query.Where = null;
matched = true;
}
}
else
{
if (logical.Operator == ExpressionOperator.And)
{
if (relational == logical.Left)
{
logical.Operator = null;
logical.Left = null;
matched = true;
}
else if (relational == logical.Right)
{
logical.Operator = null;
logical.Right = null;
matched = true;
}
}
}
if (matched)
{
SetTop(query, limit);
}
else
{
limit = -1;
}
}
}
}
if (limit <= 0)
{
throw new InvalidOperationException(
"MS engines do not have ROWNUM.");
}
}
}