Question

Hi
I’m trying to connect MySql using C in my project and it’s the first time I use C and MySql.
I try to save a user name, password and role in MySql. When I run the program like that it’s ok.

 #include <mysql.h>
 #include <stdio.h>

 main() {
MYSQL *conn;
MYSQL_RES *res;
MYSQL_ROW row;

char *server = "localhost";
char *user = "root";
char *password = "admin"; /* set me first */
char *database = "profile";
char query[500];
memset(query,0,500);
conn = mysql_init(NULL);

/* Connect to database */
if (!mysql_real_connect(conn, server,
     user, password, database, 0, NULL, 0)) {
  fprintf(stderr, "%s\n", mysql_error(conn));
  exit(1);
}
int i =2;
/* send SQL query */
char userName[45] ="hi";
char userPassword[45];
char role[45];
strcpy(userName,"koko");
strcpy(userPassword,"hi");
strcpy(role,"admin");

sprintf(query,"insert into userTbl(name,password,role) values (\'%s\',\'%s\',\'%s\'); ",userName,userPassword,role);

if (mysql_query(conn, query)) {
  fprintf(stderr, "%s\n", mysql_error(conn));
  exit(2);
}


/* close connection */
mysql_close(conn);
}

I can run it without any errors though there are some warnings.
But when i wrote this program by using function, I got this error when I compile it .
Access denied for user ‘root’@’localhost’ (using password: YES)

#include <mysql.h>
#include <stdio.h>


MYSQL *conn;
MYSQL_RES *res;
MYSQL_ROW row;

char *server = "localhost";
char *user = "root";
char *password = "admin"; /* set me first */
char *database = "profile";
void saveUser(char * , char * ,char * );
void updateUser(char * , char * ,char * );
void showData();
main() 
{
saveUser("kevin","hi","admin");
}

void saveUser(char *name, char *password,char *role)
{

char  query[500];
memset(query,0,500);
conn = mysql_init(NULL);
/* Connect to database */
if (!mysql_real_connect(conn, server,
     user, password, database, 0, NULL, 0)) {
  fprintf(stderr, "%s\n", mysql_error(conn));
  exit(1);
}
int i =2;
/* send SQL query */
sprintf(query,"insert into userTbl(name,password,role) values (\'%s\',\'%s\',\'%s\'); ",name,password,role);
if (mysql_query(conn, query)) {
  fprintf(stderr, "%s\n", mysql_error(conn));
  exit(2);
}

res = mysql_use_result(conn);



/* close connection */
mysql_free_result(res);
mysql_close(conn);
}

void updateUser(char *name, char *password,char *role)
{

char  query[500];
memset(query,0,500);
conn = mysql_init(NULL);

/* Connect to database */
if (!mysql_real_connect(conn, server,
     user, password, database, 0, NULL, 0)) {
  printf("1234511\n");
  fprintf(stderr, "%s\n", mysql_error(conn));
  exit(1);
}
int i =2;
/* send SQL query */
sprintf(query,"update userTbl set password=\'%s\',role=\'%s\' where name=\'%s\'; ",password,role,name);
if (mysql_query(conn, query)) {
  fprintf(stderr, "%s\n", mysql_error(conn));
  exit(2);
}


/* close connection */
mysql_close(conn);
}

void showData()
{
/* output table name */
system("clear");
printf("MySQL Tables in mysql database:\n");
while ((row = mysql_fetch_row(res)) != NULL)
  printf("%s \n", row[0]);
}

Can anybody explain me where I went wrong and how can I correct it.
I use gcc to get the executable file and run it on command prompt.
Thanks in advance.

Kevin

Answer 1

Hi both Simon and Devjosh , Thanks for you help. I found the problem._The global variable name password is the same with the parameter name password in saveUser function _. Thanks a lot and so sorry disturb you .

Kevin