Adding query conditions
An Apama query can specify conditions that must be satisfied for there to be a match for the event pattern of interest. You can specify the following kinds of conditions:
Filter — This is a Boolean expression that refers to the events in the specified pattern of interest. This expression must evaluate to
true for there to be a match. There can be zero, one, or more query filter conditions. Adding a query filter condition inserts a
where clause in the source view of the query.
Time constraint — This is a time period during which some or all events in the pattern must have been received. There can be zero, one, or more time constraints. Adding a time constraint inserts a
within clause in the source view of the query.
Exclusion — This is the specification of an event whose presence prevents a match. If you need to prevent a match only when instances of this event have certain values you can add a filter that qualifies which instances of the specified event prevent a match. You can add zero, one or more exclusions. Adding an exclusion inserts a
without clause in the source view of the query.
You add query conditions in the
Conditions pane of the
Design view. Click the down arrow to the right of the plus sign (
) and select the kind of condition you want to add. Query Designer displays a dialog in which you define the condition.
After you add a condition in the Design view, it appears in a row in the Conditions pane that shows the condition type, the expression that specifies the condition, and the range that the condition applies to if one was specified. Select the condition to edit or delete it.
When you add a condition it is immediately added to the source code. Any changes you make in the Source tab will be shown in the Design tab, and vice versa. If you introduce any errors into the query source code then you must resolve them in the Source tab before you can view the query in the Design tab.
For more details about the EPL code for query conditions, see
Query conditions.