Redigera

Dela via

Querying Embedded Objects

  • Artikel

You have several options as to the form a query takes when querying an event class that contains embedded objects. The results returned by the query vary, depending on the form of the query you use.

Class Definitions

The following example shows the class definitions that are used for the WQL queries in this topic.

class MyClass
{
   string Prop1;
   string Prop2;
};

class MyEvent : __ExtrinsicEvent
{
   MyClass E1;
   MyClass E2;
};

Examples

The following query returns both embedded classes, E1 and E2, each having Prop1 and Prop2 populated with data.

SELECT * FROM MyEvent

The following query returns the E1 embedded object, but with neither Prop1 nor Prop2 populated with data.

SELECT E1 FROM MyEvent

The following query returns the embedded class E1 with only Prop1 populated with data.

SELECT E1.Prop1 FROM MyEvent

The following query returns both embedded classes, E1 and E2, each having Prop1 and Prop2 populated with data.

ELECT E1.Prop1, E1.Prop2, E2.Prop1, E2.Prop2 FROM MyEvent

This is equivalent to the first query using the asterisk (*) instead of specifying each object and property.

Querying with WQL