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GNOME Data Access 4.0 manual | ![]() |
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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 ("SimpleExample", "1.0", argc, argv); 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)