mysql_select_db(3) MariaDB Connector/C mysql_select_db(3)

mysql_select_db - selects a database as default

#include <mysql.h>
int mysql_select_db(MYSQL * mysql,
                    const char * db);

Selects a database as default. Returns zero on success, non-zero on failure

mysql is a connection identifier, which was previously allocated by mysql_init(3) and connected by mysql_real_connect(3).
db - the default database name

To retrieve the name of the default database either execute the SQL command SELECT DATABASE() or retrieve the value via mariadb_get_infov(3) API function.
The default database can also be set by the db parameter in mysql_real_connect(3).

# switch to default database test
USE test;
# check default database
SELECT DATABASE();
+------------+
| database() |
+------------+
| test       |
+------------+

static int set_default_db(MYSQL *mysql)
{
  int rc;
  char *default_db;
  /* change default database to test */
  rc= mysql_select_db(mysql, "test");
  if (rc)
    return rc;  /* Error */
  /* get the default database */
  rc= mariadb_get_infov(mysql, MARIADB_CONNECTION_SCHEMA, &default_db);
  if (rc)
    return rc; /* Error */
  if (strcmp("test", default_db) != NULL)
  {
    printf("Wrong default database\n");
    return 1;
  }
  printf("Default database: %s", default_db);
  return 0;
}

mysql_real_connect(3)

Version 3.4