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.
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 |
In order
to run continual queries at the server, you MUST first
go to "Registration" (make sure your email address is correct),
then go to "Install CQ". But you may use "Normal Query" without
registration. To view or remove your installed CQ, use "Browse CQ". |