/// <summary>
/// Given a <i>HAVING</i> clause expression, this will generate
/// a new <i>HAVING</i> clause expression with all aggregate
/// expressions put into the given extra function list.
/// </summary>
/// <param name="havingExpr"></param>
/// <param name="aggregateList"></param>
/// <param name="context"></param>
/// <returns></returns>
private static Expression FilterHavingClause(Expression havingExpr, IList <Expression> aggregateList, IQueryContext context)
{
if (havingExpr is BinaryExpression)
{
var binary = (BinaryExpression)havingExpr;
Operator op = binary.Operator;
// If logical, split and filter the left and right expressions
Expression[] exps = { binary.Left, binary.Right };
Expression newLeft = FilterHavingClause(exps[0], aggregateList, context);
Expression newRight = FilterHavingClause(exps[1], aggregateList, context);
Expression expr = Expression.Binary(newLeft, op.AsExpressionType(), newRight);
return(expr);
}
// Not logical so determine if the expression is an aggregate or not
if (havingExpr.HasAggregateFunction(context))
{
// Has aggregate functions so we must WriteByte this expression on the
// aggregate list.
aggregateList.Add(havingExpr);
// And substitute it with a variable reference.
ObjectName v = ObjectName.Parse("FUNCTIONTABLE.HAVINGAG_" + aggregateList.Count);
return(Expression.Variable(v));
}
// No aggregate functions so leave it as is.
return(havingExpr);
}
private static bool CompareCells(DataObject ob1, DataObject ob2, Operator op)
{
var exp = Expression.Binary(Expression.Constant(ob1), op.AsExpressionType(), Expression.Constant(ob2));
DataObject result = exp.Evaluate();
// NOTE: This will be a NullPointerException if the result is not a
// boolean type.
//TODO: check...
bool?bresult = result.ToBoolean();
if (!bresult.HasValue)
{
throw new NullReferenceException();
}
return(bresult.Value);
}
/// <summary>
/// Adds a single var plan to the given list.
/// </summary>
/// <param name="list"></param>
/// <param name="table"></param>
/// <param name="variable"></param>
/// <param name="singleVar"></param>
/// <param name="expParts"></param>
/// <param name="op"></param>
private static void AddSingleVarPlanTo(IList<SingleVarPlan> list, PlanTableSource table, ObjectName variable, ObjectName singleVar, Expression[] expParts, Operator op)
{
var exp = Expression.Binary(expParts[0], op.AsExpressionType(), expParts[1]);
// Is this source in the list already?
foreach (SingleVarPlan plan1 in list) {
if (plan1.TableSource == table &&
(variable == null || plan1.Variable.Equals(variable))) {
// Append to end of current expression
plan1.Variable = variable;
plan1.Expression = Expression.And(plan1.Expression, exp);
return;
}
}
// Didn't find so make a new entry in the list.
SingleVarPlan plan = new SingleVarPlan();
plan.TableSource = table;
plan.Variable = variable;
plan.SingleVariable = singleVar;
plan.Expression = exp;
list.Add(plan);
return;
}
