protected override void VisitSingleRowSubselect(BoundSingleRowSubselect node)
{
var output = node.Relation.GetOutputValues().Single();
ValueSlots.Add(output);
base.VisitSingleRowSubselect(node);
}
protected override BoundExpression RewriteSingleRowSubselect(BoundSingleRowSubselect node)
{
var input = RewriteRelation(node.Relation);
var valueSlot = RewriteValueSlot(node.Value);
return(node.Update(valueSlot, input));
}
protected override BoundExpression RewriteSingleRowSubselect(BoundSingleRowSubselect node)
{
var relation = RewriteRelation(node.Relation);
var factory = node.Value.Factory;
// TODO: If the query is guranteed to return a single, e.g. if it is a aggregated but not grouped,
// we should not emit the additional aggregation and assertion.
// 1. We need to know whether it returns more then one row.
var valueSlot = node.Value;
var anyOutput = factory.CreateTemporary(valueSlot.Type);
var countOutput = factory.CreateTemporary(typeof(int));
var anyAggregateSymbol = BuiltInAggregates.Any;
var anyAggregatable = anyAggregateSymbol.Definition.CreateAggregatable(valueSlot.Type);
var countAggregatedSymbol = BuiltInAggregates.Count;
var countAggregatable = countAggregatedSymbol.Definition.CreateAggregatable(typeof(int));
var aggregates = new[]
{
new BoundAggregatedValue(anyOutput, anyAggregateSymbol, anyAggregatable, Expression.Value(valueSlot)),
new BoundAggregatedValue(countOutput, countAggregatedSymbol, countAggregatable, Expression.Literal(0))
};
var aggregation = new BoundGroupByAndAggregationRelation(relation, Enumerable.Empty <BoundComparedValue>(), aggregates);
// 2. Now we can assert that the number of rows returned is at most one.
var condition = Expression.LessThan(Expression.Value(countOutput), Expression.Literal(1));
var message = Resources.SubqueryReturnedMoreThanRow;
var assertRelation = new BoundAssertRelation(aggregation, condition, message);
var subquery = new Subquery(SubqueryKind.Subselect, anyOutput, assertRelation, CurrentPassthru);
var subqueries = _subqueryStack.Peek();
subqueries.Add(subquery);
return(Expression.Value(anyOutput));
}
protected override BoundExpression RewriteSingleRowSubselect(BoundSingleRowSubselect node)
{
_recorder.Record(node.Value);
return(base.RewriteSingleRowSubselect(node));
}
protected override void VisitSingleRowSubselect(BoundSingleRowSubselect node)
{
SubqueryFound = true;
}
