Author: Written by Bruce Momjian (<email@example.com>) and last updated 2002-03-04
pgeasy allows you to cleanly interface to the libpq library, more like a 4GL SQL interface. Refer to Chapter 1 for more information about libpq.
It consists of a set of simplified C functions that encapsulate the functionality of libpq. The functions are:
PGresult *doquery(char *query);
PGconn *connectdb(char *options);
int fetch(void *param,...);
int fetchwithnulls(void *param,...);
void set_result(PGresult *newres);
Many functions return a structure or value, so you can work with the result if required.
You basically connect to the database with connectdb, issue your query with doquery, fetch the results with fetch, and finish with disconnectdb.
For SELECT queries, fetch allows you to pass pointers as parameters, and on return the variables are filled with data from the binary cursor you opened. These binary cursors cannot be used if you are running the pgeasy client on a system with a different architecture than the database server. If you pass a NULL pointer parameter, the column is skipped. fetchwithnulls allows you to retrieve the NULL status of the field by passing an int* after each result pointer, which returns true or false to indicate if the field is null. You can always use libpq functions on the PGresult pointer returned by doquery. reset_fetch starts the fetch back at the beginning.
get_result and set_result allow you to handle multiple open result sets. Use get_result to save a result into an application variable. You can then later use set_result to return to the previously save result.
There are several demonstration programs in pgsql/src/interfaces/libpgeasy/examples.