One SQL and C question

[QQ]

In C and SQL I write a very simple program and it works
However when I try to create a MYSQL object and call it in the
function,
it fails. Here is my program, what's wrong? Thanks a lot!

#include <stdlib.h>
#include <stdio.h>
#include "mysql.h"
int main(int argc, char *argv[]) {
MYSQL my_connection;
mysql_init(&my_connection);
if (mysql_real_connect(&my_connection, "localhost", "","", "",
0, NULL, 0))
{
printf("Connection success\n");
db_Roamer_Create("testtest");
}
else
{
fprintf(stderr, "Connection failed\n");
if (mysql_errno(&my_connection))
{
fprintf(stderr, "Connection error %d: %s\n",
mysql_errno(&my_connection), mysql_error(&my_connection));
}
}
mysql_close(&my_connection);

}

int db_Roamer_Create(MYSQL *my_connection,const char *dbname)
{
printf("dbName is %s\n",dbname);
char *cmd;
if ( ( cmd = malloc( strlen( "CREATE DATABASE " ) +
strlen( dbname ) + 1 ) ) == NULL ) {
fprintf( stderr, "Running out of memory!\n" );
exit( EXIT_FAILURE );
}
sprintf(cmd,"CREATE DATABASE %s;",dbname);

if(mysql_query(my_connection,cmd)==0)
{
printf("Create Database sucessfully");
}
else
{
fprintf(stderr, "Create Database failed\n");
if (mysql_errno(my_connection)) {
fprintf(stderr, "Create Database error %d: %s\n",
mysql_errno(my_connection), mysql_error(my_connection));
}
}
}

[SM Ryan]

# int db_Roamer_Create(MYSQL *my_connection,const char *dbname)
# {
# printf("dbName is %s\n",dbname);
# char *cmd;
# if ( ( cmd = malloc( strlen( "CREATE DATABASE " ) +
# strlen( dbname ) + 1 ) ) == NULL ) {
# fprintf( stderr, "Running out of memory!\n" );
# exit( EXIT_FAILURE );
# }
# sprintf(cmd,"CREATE DATABASE %s;",dbname);

(1) Your malloc is one character short. You need +1 for the ";" and +1 for the
string terminator. My way of doing this would be
static char F[] = "CREATE DATABASE %s;";
char *f = malloc(sizeof F + strlen(dbname));
sprintf(f,F,dbname);

(2) HOWEVER--Don't include the ';' terminator. That's an artifact of marking
the end of the command when read from a terminal. You don't use it when you
call mysql_query.

--
SM Ryan http://www.rawbw.com/~wyrmwif/
Leave it to the Catholics to destroy existence.

[poison.summer]

Thanks a lot

However, my program works if I define MYSQL my_connection
to be a global variable.

Any reason for that?

[Gordon Burditt]

>In C and SQL I write a very simple program and it works

However when I try to create a MYSQL object and call it in the
function,
it fails.
There is no place in your program where it can print "it fails".
*HOW* does it fail? You deserve to have it fail in mysql_real_connect()
for not putting a password on your database, even if it is accessible
only to localhost. You are also obviously out of disk space.

You call db_Roamer_Create with *one* argument, yet define it with
two. Why? Didn't your compiler warn you about that?
Here is my program, what's wrong? Thanks a lot!

#include <stdlib.h>
#include <stdio.h>
#include "mysql.h"
int main(int argc, char *argv[]) {
MYSQL my_connection;
mysql_init(&my_connection);
if (mysql_real_connect(&my_connection, "localhost", "","", "",
0, NULL, 0))
{
printf("Connection success\n");
db_Roamer_Create("testtest");
}
else
{
fprintf(stderr, "Connection failed\n");
if (mysql_errno(&my_connection))
{
fprintf(stderr, "Connection error %d: %s\n",
mysql_errno(&my_connection), mysql_error(&my_connection));
}
}
mysql_close(&my_connection);

}

int db_Roamer_Create(MYSQL *my_connection,const char *dbname)
{
printf("dbName is %s\n",dbname);
char *cmd;
if ( ( cmd = malloc( strlen( "CREATE DATABASE " ) +
strlen( dbname ) + 1 ) ) == NULL ) {
You malloc() insufficient memory here for what you want to put in it.
fprintf( stderr, "Running out of memory!\n" );
exit( EXIT_FAILURE );
}
sprintf(cmd,"CREATE DATABASE %s;",dbname);

if(mysql_query(my_connection,cmd)==0)
{
printf("Create Database sucessfully");
}
else
{
fprintf(stderr, "Create Database failed\n");
if (mysql_errno(my_connection)) {
fprintf(stderr, "Create Database error %d: %s\n",
mysql_errno(my_connection), mysql_error(my_connection));
}
}
}

[SM Ryan]

po***********@gmail.com wrote:
# Thanks a lot
#
# However, my program works if I define MYSQL my_connection
# to be a global variable.

Are you passing in the value if it's a parameter?

--
SM Ryan http://www.rawbw.com/~wyrmwif/
God's a skeeball fanatic.

[QQ]

No
if I pass it as a parameter
it fails,

if I define it as a global
it works

feell weired

[Keith Thompson]

"QQ" <ju****@yahoo.com> writes:

No
if I pass it as a parameter
it fails,

if I define it as a global
it works

feell weired

What???

Please don't assume that your readers have easy access to the article
to which you're replying. Provide some context.

If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.