Re: Variable array sizes with PQexecParams

(Sorry I sent this to you twice, Tom. I forgot to CC to the
pgsql-novice list.)

Thanks a lot, Tom.

One follow-up question:
If I want the number of elements in that array to vary with each
execution, then I'd have to use the $1="'{foo,bar}'" method right?
Then, I'd construct that string based on the number of elements I have
for that execution.

Josh

-----Original Message-----
From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
Sent: Monday, June 26, 2006 1:32 PM
To: Garcia, Joshua
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: [NOVICE] Variable array sizes with PQexecParams

"Garcia, Joshua" <Joshua(dot)Garcia(at)xerox(dot)com> writes:
> I want to use PQexecParams to insert into a field that takes an array
of
> varchars. I tried something like:
> INSERT INTO table1(column1) VALUES ('{$1,$2}')
> But, this just inserts {$1,$2} into the field.

Well, yeah. If it did anything else that'd be a catastrophic bug.

Try something like

INSERT INTO table1(column1) VALUES (ARRAY[$1,$2])

For varchar this will probably work as-is, for other datatypes you might
need to add explicit casts to determine the array element types, eg

INSERT INTO table1(column1) VALUES (ARRAY[$1::integer,$2::integer])

Another possibility is to treat the whole array value as one parameter:

INSERT INTO table1(column1) VALUES ($1)

where the value of $1 is like "{foo,bar}", but this gets into having to
quote the data values correctly to make them valid array elements. The
first way is probably safer.

regards, tom lane