Hi!

Sorry to bother you with what may seem a novice question (maybe it has been already answered somewhere in this forum or on the documentation, but somehow I must have missed it), but it's really bugging me. How can I implement a SELECT COUNT(0) or SELECT COUNT(*) using the GetScalar method on the Adapter scenario?

Thanks in advance.

You can use the GetDBCount method here is a bit from the documentation for it.

// C#
OrderCollection orders = new OrderCollection();
IPredicateExpression filter = new PredicateExpression();
filter.Add(PredicateFactory.CompareValue(CustomerFieldIndex.Country, ComparisonOperator.Equal, "France"));
IRelationCollection relations = new RelationCollection();
relations.Add(OrderEntity.Relations.CustomerEntityUsingCustomerId);
int amount = orders.GetDbCount(filter, relations);
' VB.NET
Dim orders As New OrderCollection()
Dim filter As IPredicateExpression = New PredicateExpression()
filter.Add(PredicateFactory.CompareValue(CustomerFieldIndex.Country, ComparisonOperator.Equal, "France"))
Dim relations As IRelationCollection = New RelationCollection()
relations.Add(OrderEntity.Relations.CustomerEntityUsingCustomerId)
Dim amount As Integer = orders.GetDbCount(filter, relations)

The number is retrieved by using the GetScalar() method of the entity collection class, using the Count(*) aggregate function. See for more details about using Aggregate functions in your code the section Field expressions and aggregates.

bclubb wrote:

You can use the GetDBCount method here is a bit from the documentation for it.

// C#
OrderCollection orders = new OrderCollection();
IPredicateExpression filter = new PredicateExpression();
filter.Add(PredicateFactory.CompareValue(CustomerFieldIndex.Country, ComparisonOperator.Equal, "France"));
IRelationCollection relations = new RelationCollection();
relations.Add(OrderEntity.Relations.CustomerEntityUsingCustomerId);
int amount = orders.GetDbCount(filter, relations);
' VB.NET
Dim orders As New OrderCollection()
Dim filter As IPredicateExpression = New PredicateExpression()
filter.Add(PredicateFactory.CompareValue(CustomerFieldIndex.Country, ComparisonOperator.Equal, "France"))
Dim relations As IRelationCollection = New RelationCollection()
relations.Add(OrderEntity.Relations.CustomerEntityUsingCustomerId)
Dim amount As Integer = orders.GetDbCount(filter, relations)

The number is retrieved by using the GetScalar() method of the entity collection class, using the Count(*) aggregate function. See for more details about using Aggregate functions in your code the section Field expressions and aggregates.

I'm going to admit that this block of code has never made sense to me. I think I understand now that GetDbCount is a function that exists only in SelfServicing, not in Adapter, and since I never use SelfServicing I couldn't find GetDbCount.

Am I wrong? Is there a GetDbCount tucked away in Adapter somewhere?

The following sample was copied from the LLBLGen Pro documentation, "Using the generated code - Field expressions and aggregates - Aggregate functions in scalar queries"

DataAccessAdapter adapter = new DataAccessAdapter();
IExpression productPriceExpression = new Expression(
    OrderDetailsFields.Quantity, ExOp.Mul, OrderDetailsFields.UnitPrice);
IPredicate filter = PredicateFactory.CompareValue(OrderDetailsFieldIndex.OrderId, ComparisonOperator.Equal, 10254);

[b]decimal orderPrice = (decimal)adapter.GetScalar(OrderDetailsFields.OrderId, 
        productPriceExpression, AggregateFunction.Sum, filter);[/b]

you can AggregateFunction.Count instead of AggregateFunction.Sum, and you can always have the Count(*) by having the Count(PK)

So mainly the following will get you going:

int nCount = (int)adapter.GetScalar(EntityNameFields.PK, AggregateFunction.Count);

You also can use DataAccessAdapter.GetDbCount() (one of the 4 overloads). The GetDbCount is used for getting the count of the rowset returned by a given query. GetScalar() is a method you can also use to retrieve the db count, for example for individual fields. GetDbCount is thus another alternative