Table of Contents for

MySQL in a Nutshell, 2nd Edition

Use this to establish a connection to a MySQL server. The MYSQL structure created by mysql_init() is given as the first argument to the function. The hostname, username, and user’s password for connecting to the server are given next. The name of the database is given as the fifth argument. The port, the socket file path and name for Unix systems, and any client flags are given as the sixth, seventh, and eighth arguments, respectively. For any parameter requiring a char pointer, a value of NULL may be given to instruct the server to use the default setting. For unsigned int variables, a value of 0 may be given to rely on the default value. Here is an example:

#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>
int main(void)
{
  MYSQL *mysql;
  MYSQL_RES *result;
  MYSQL_ROW row;
  MYSQL_FIELD *field;
  const char *host = "localhost";
  const char *user = "root";
  const char *password = "my_password";
  const char *database = "workrequests";
  unsigned int port = 3306;
  const char *socket = NULL;
  unsigned long flag = 0;
  int i, num_fields;
  mysql = mysql_init(NULL);
  mysql_real_connect(mysql,host,user,password,database,
                     port,socket,flag);
  const char *sql_stmnt = "SELECT * FROM stores";
  ulong bytes = strlen(sql_stmnt);
  mysql_real_query(mysql, sql_stmnt, bytes);
  result = mysql_store_result(mysql);
  num_fields = mysql_field_count(mysql);
  while((row = mysql_fetch_row(result)) != NULL)
     {
      for(i = 0; i < num_fields; i++)
        { printf("%s, ", row[i]); }
      printf("\n");
     }
  mysql_free_result(result);
  mysql_close(mysql);
  return 0;
}

This example is fairly complete. Each variable is declared at the beginning based on the type called for by the function, along with its respective values. Without having to disconnect and reconnect, you can change the database using the mysql_select_db() function.