/// <summary>
/// Augments a node with a number of OuterApply's - one for each subquery
/// If S1, S2, ... are the list of subqueries for the node, and D is the
/// original (driver) input, we convert D into
/// OuterApply(OuterApply(D, S1), S2), ...
/// </summary>
/// <param name="input">the input (driver) node</param>
/// <param name="subqueries">List of subqueries</param>
/// <param name="inputFirst">should the input node be first in the apply chain, or the last?</param>
/// <returns>The resulting node tree</returns>
private Node AugmentWithSubqueries(Node input, List <Node> subqueries, bool inputFirst)
{
Node newNode;
int subqueriesStartPos;
if (inputFirst)
{
newNode = input;
subqueriesStartPos = 0;
}
else
{
newNode = subqueries[0];
subqueriesStartPos = 1;
}
for (int i = subqueriesStartPos; i < subqueries.Count; i++)
{
OuterApplyOp op = m_command.CreateOuterApplyOp();
newNode = m_command.CreateNode(op, newNode, subqueries[i]);
}
if (!inputFirst)
{
// The driver node uses a cross apply to ensure that no results are produced
// for an empty driver.
newNode = m_command.CreateNode(m_command.CreateCrossApplyOp(), newNode, input);
}
// We may need to perform join elimination
m_compilerState.MarkPhaseAsNeeded(PlanCompilerPhase.JoinElimination);
return(newNode);
}
/// <summary>
/// Visitor pattern method for OuterApplyOp
/// </summary>
/// <param name="op"> The OuterApplyOp being visited </param>
/// <param name="n"> The Node that references the Op </param>
public virtual void Visit(OuterApplyOp op, Node n)
{
VisitApplyOp(op, n);
}
// <summary>
// Clone an OuterApplyOp
// </summary>
// <param name="op"> The Op to Copy </param>
// <param name="n"> The Node that references the Op </param>
// <returns> A copy of the original Node that references a copy of the original Op </returns>
public override Node Visit(OuterApplyOp op, Node n)
{
return CopyDefault(m_destCmd.CreateOuterApplyOp(), n);
}