MySql from C on Ubuntu

Question

I can use mysql from terminal to query data and I try to connect to mysql server with C but here is some problem i don't know to fix but seems like version conflict.

#include <my_global.h>
#include <mysql.h>

int main(int argc, char **argv)
{
  MYSQL *conn;
  conn = mysql_init(NULL);
  if (conn == NULL) {
      printf("Error %u: %s\n", mysql_errno(conn), mysql_error(conn));
      exit(1);
}

// upper code works

// following don't work...
if (mysql_real_connect(conn, "localhost", "username", "password", NULL, 0, NULL, 0) == NULL)
{
  printf("Error %u: %s\n", mysql_errno(conn), mysql_error(conn));
  exit(1);
}
etc...

When I start this code message "Error 2002: Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)" appears. Problem is that I don't have mysql.sock anywhere in computer but have /var/run/mysqld/mysqld.sock. In linker options I added /var/lib/libmysql.so and program compiles OK.

Is here any simple way to get this to work?

Jan Vorcak · Accepted Answer · 2011-12-08 14:32:03Z

2

why not connecting directly to the socket?

mysql_real_connect(conn, "localhost", "username", "password",
                   NULL, 0, "/var/run/mysqld/mysqld.sock", 0)

I have no environment to test it right now, but I think it should work

To answer question in your comment:

I think its' because of your configuration, mysql's default configuration is to store socket at /tmp/mysql.sock, and it didn't find it there, you just specified your location of the socket, this is not a portable solution, it depends on purpose of your application

edited Dec 8, 2011 at 14:32

answered Dec 8, 2011 at 13:56

Jan Vorcak

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4 Comments

Wine Too Over a year ago

WOW, man, thanks a million. My first connection ever to mysql from C now WORKS :)) Is this propper use and why I get those error?

Amal Antony Over a year ago

U got the error because C was looking for the socket at the location /tmp/mysql.sock which doesn't exist.

Wine Too Over a year ago

But why would C looks to /tmp/mysql.sock? From where he got this information?

Wine Too Over a year ago

This can be a problem for deploying programs. So, after all I find solution. Here is possible to create link to /var/run/mysqld/mysqld.sock, copy this link to tmp/ and rename it to mysql.sock. Then everything works as expected.

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