| GNOME Data Access 4.0 manual |
|---|
The following example is a complete program which creates a example_db.db SQLite database in the current directory, creates a "products" table,add a few rows to it, and then displays its contents. The example uses an SQLite database as it does not require any server setup and can thus be run as-is. That example can be found in the samples/SimpleExample/example.c.
To compile it, run:
cc -o example example.c `pkg-config --cflags --libs libgda-3.0`
The code is:
#include <libgda/libgda.h>
#include <sql-parser/gda-sql-parser.h>
GdaConnection *open_connection (void);
void display_products_contents (GdaConnection *cnc);
void create_table (GdaConnection *cnc);
void run_sql_non_select (GdaConnection *cnc, const gchar *sql);
int
main (int argc, char *argv[])
{
gda_init ();
GdaConnection *cnc;
/* open connections */
cnc = open_connection ();
create_table (cnc);
display_products_contents (cnc);
gda_connection_close (cnc);
return 0;
}
/*
* Open a connection to the example.db file
*/
GdaConnection *
open_connection (void)
{
GdaConnection *cnc;
GError *error = NULL;
GdaSqlParser *parser;
/* open connection */
cnc = gda_connection_open_from_string ("SQLite", "DB_DIR=.;DB_NAME=example_db", NULL,
GDA_CONNECTION_OPTIONS_NONE, &error);
if (!cnc) {
g_print ("Could not open connection to SQLite database in example_db.db file: %s\n",
error && error->message ? error->message : "No detail");
exit (1);
}
/* create an SQL parser */
parser = gda_connection_create_parser (cnc);
if (!parser) /* @cnc doe snot provide its own parser => use default one */
parser = gda_sql_parser_new ();
/* attach the parser object to the connection */
g_object_set_data_full (G_OBJECT (cnc), "parser", parser, g_object_unref);
return cnc;
}
/*
* Create a "products" table
*/
void
create_table (GdaConnection *cnc)
{
run_sql_non_select (cnc, "DROP table IF EXISTS products");
run_sql_non_select (cnc, "CREATE table products (ref string not null primary key, "
"name string not null, price real)");
run_sql_non_select (cnc, "INSERT INTO products VALUES ('p1', 'chair', 2.0)");
run_sql_non_select (cnc, "INSERT INTO products VALUES ('p2', 'table', 5.0)");
run_sql_non_select (cnc, "INSERT INTO products VALUES ('p3', 'glass', 1.1)");
}
/*
* display the contents of the 'products' table
*/
void
display_products_contents (GdaConnection *cnc)
{
GdaDataModel *data_model;
GdaSqlParser *parser;
GdaStatement *stmt;
gchar *sql = "SELECT ref, name, price FROM products";
GError *error = NULL;
parser = g_object_get_data (G_OBJECT (cnc), "parser");
stmt = gda_sql_parser_parse_string (parser, sql, NULL, NULL);
data_model = gda_connection_statement_execute_select (cnc, stmt, NULL, &error);
g_object_unref (stmt);
if (!data_model)
g_error ("Could not get the contents of the 'products' table: %s\n",
error && error->message ? error->message : "No detail");
gda_data_model_dump (data_model, stdout);
g_object_unref (data_model);
}
/*
* run a non SELECT command and stops if an error occurs
*/
void
run_sql_non_select (GdaConnection *cnc, const gchar *sql)
{
GdaStatement *stmt;
GError *error = NULL;
gint nrows;
const gchar *remain;
GdaSqlParser *parser;
parser = g_object_get_data (G_OBJECT (cnc), "parser");
stmt = gda_sql_parser_parse_string (parser, sql, &remain, &error);
if (remain)
g_print ("REMAINS: %s\n", remain);
nrows = gda_connection_statement_execute_non_select (cnc, stmt, NULL, NULL, &error);
if (nrows == -1)
g_error ("NON SELECT error: %s\n", error && error->message ? error->message : "no detail");
g_object_unref (stmt);
}
and executing should output something like:
> ./example
ref | name | price
----+-------+---------
p1 | chair | 2.000000
p2 | table | 5.000000
p3 | glass | 1.100000
(3 rows)