PostgreSQL's libpq and SELECT FROM

Question

I have code like below (it's partial, ofcourse). I can connect sucessfully to the database, I can do INSERT INTO and all that stuff, but the result of SELECT FROM never can be displayed.

snprintf(sqlSelect, sizeof(sqlSelect), "select * from %s", sqlTableName);

res = PQexec(conn, sqlSelect);
if (PQresultStatus(res) != PGRES_TUPLES_OK) {
    fprintf(stderr, "SELECT FROM failed: %s", PQerrorMessage(conn));
    PQclear(res);
    exitNicely(conn);
}

PQclear(res);

Why above code doesn't print SELECT * FROM db_name result in the terminal?

I don't get any kind of error. Just "blank" line which should indicate that `SELECT` command was successfully passed to the server. — Teddy, Feb 08 '13 at 19:47
I don't see any code which would *print* the query result (and no, it doesn't happen automatically) — Anton Kovalenko, Feb 08 '13 at 19:48
Steal something from http://www.postgresql.org/docs/9.2/static/libpq-example.html (start with `print out the rows` part of the first example) — Anton Kovalenko, Feb 08 '13 at 19:53
@AntonKovalenko: Looks like you should make that into an answer. — Erwin Brandstetter, Feb 09 '13 at 12:45

score 1 · Answer 1 · answered Feb 10 '13 at 03:04

The code doesn't print out or otherwise use the result rows, it just fetches them and throws them away.

You need to iterate over the result set and actually do something with it. See the libpq examples for some ways to do this.

(CW because I'm just converting Erwin's point into an answer).

PostgreSQL's libpq and SELECT FROM

1 Answers1