Re:

> I'm having trouble getting my head round setting up a composite foreign
key. For example, consider the following:

> CREATE TABLE sensorID (
> SensorID VARCHAR (30) PRIMARY KEY
> );

> CREATE TABLE time (
> SensorID VARCHAR (30) references sensorID(SensorID),
> Time time without time zone,
> Date date,
> CONSTRAINT Time_Pkey PRIMARY KEY (SensorID, Time, Date)
> );

> So far so good. However, I now want to set up another table that uses
time.Time_Pkey as its foreign key, but I can't see how to do it. For
example, something like:

> CREATE TABLE notification (
> Time_Fkey ??????
> FOREIGN KEY (Time_Fkey) references time(Time_Pkey),
> Reason VARCHAR (30)
> );

> What needs to go into "??????" ? Can I even do something like this? Or
can I do it with indexes? If so, help please?

Something like this?
CREATE TABLE notification (
SensorID VARCHAR (30),
Time time without time zone,
Date date,
Reason VARCHAR (30),
CONSTRAINT fk_1 FOREIGN KEY (sensorid,time,date) references
time(sensorid,time,date)

);
By the way,I don't think it is a good idea to name columns as Time, Date
etc..
Regards,
Jayadevan

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