In DObject O/R Mapping persistence layer, in order to get object and object-set, you can query in the way of using OQL that based on native language.
l Using OQL conditional expression query to get object:
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var customer : ICustomer; begin customer := TCustomer.GetByCriteria(ObjectManager, OQL.Criteria(NW.Customer.CustomerID).Equal('ALFKI') ); end; |
l The OQL conditional expression above can be complex at will as follows:
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var qryOrders : ISelectQuery; customer : ICustomer; begin qryOrders := TSelectQuery.Create; qryOrders .Select(NW.Order.CustomerID) .From(NW.Order) .Where( OQL.Criteria(NW.Order.ShipCity).EQ(' customer := TCustomer.GetByCriteria(ObjectManager, OQL.Criteria(NW.Customer.CustomerID).In_(qryOrders) ); end; |
l The way to get object-set is similar, a sample is as follows:
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var qryOrders : ISelectQuery; customers : IObjectSet; begin qryOrders := TSelectQuery.Create; qryOrders .Select(NW.Order.CustomerID) .From(NW.Order) .Where( OQL.Criteria(NW.Order.ShipCity).EQ(' customers := ObjectManager.GetObjectSet(NW.Customer, OQL.Criteria(NW.Customer.CustomerID).In_(qryOrders) ); // ... end; |
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