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up vote 1 down vote favorite

I am trying to write a program in C using the MYSQL C API. I have everything working, except recently I have been getting an error when trying to connect to a server. No matter what server I connect to, it continues to give me "mysql server has gone away.". My goal is basically to access an external server and retrieve some data. Here is the code that I have so far:

conn = mysql_init(NULL);

/* Connect to database */
if (!mysql_real_connect(conn, server,
     user, password, database, 0, NULL, 0)) {
    printf("%s",mysql_stat(conn));
    fprintf(stderr, "%s\n", mysql_error(conn));
} else {
    printf("works");
}

/* send SQL query */
if (mysql_query(conn, "show tables")) {
  fprintf(stderr, "%s\n", mysql_error(conn));
}

res = mysql_use_result(conn);

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

/* close connection */
mysql_free_result(res);
mysql_close(conn);
}
share|improve this question
    
Have you checked this page:? dev.mysql.com/doc/refman/5.0/en/gone-away.html – ypercubeᵀᴹ May 12 '11 at 7:16
    
if (mysql_query(conn, ... or if (! mysql_query(conn, ... ? – ypercubeᵀᴹ May 12 '11 at 7:21
up vote 1 down vote

I know this is an old question but I just ran across it now and I wanted to leave an answer for those who may need it in the future.

If you're getting the error "MySQL server has gone away" it means the client lost its connection to MySQL. Perhaps the MySQL server was shut down, or more likely there was no activity after a certain amount of time and the server closed the connection. Read through this page of the MySQL documentation to better understand the error: dev.mysql.com/doc/refman/5.7/en/gone-away.html

Try setting the MYSQL_OPT_RECONNECT option to 1 and see if that resolves the issue. When set, the client will attempt to reconnect automatically and this should solve the problem if it's a closed/timed-out connection. For the pertinent docs, see: dev.mysql.com/doc/refman/5.7/en/auto-reconnect.html. Keep in mind that only one re-connect attempt is performed; The query can still fail if the server is down or inaccessible.

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