Update an event in a named window when an event occurs.
Syntax:
on eventType [(filterCondition)] [as name]
update windowName [as name]
set property = expression [,property = expression] [, ...]
[where conditionExpression]
When an event of eventType occurs, this syntax updates the value of the property specified in the SET clause to the value of expression for events in the named window specified at windowName. If a WHERE clause conditionExpression is specified, only events that match that condition are targeted.
