A continual
query (CQ) is a standing query that can monitor updates at data sources
and return new query results whenever the updates have reached a specified threshold(the
trigger condition). A continual query consists of three key components: an SQL-like
query, a trigger condition, and a stop condition.
An optional component is notification condition, which specifies how
often you want to be notified about the result change.
| CQ Elements |
Examples |
 |
SQL-like query |
select COMPANYNAME, HIGH, LOW, VOLUME from stock |
 |
Trigger condition |
 Time-based |
6am every Monday |
 Content-based |
STOCK.HIGH INCBYP 20 WHERE
STOCK.COMPANYNAME = 'IBM' |
 |
Stop condition |
23pm June 1, 1999 |
 |
Notification condition |
Weekly email |
|
