Error getting output from mysql.h using C++ and g++ - c++

Question

I have a small piece of code which (should) allows me to connect to an MySQL database, here is the code:
#include <iostream>
#include <mariadb/mysql.h> // /usr/includes/mariadb/mysql.h
struct connection_details
{
const char *server, *user, *password, *database;
};
MYSQL* mysql_connection_setup(struct connection_details mysql_details){
MYSQL *connection = mysql_init(NULL); // mysql instance
//connect database
if(!mysql_real_connect(connection, mysql_details.server, mysql_details.user, mysql_details.password, mysql_details.database, 0, NULL, 0)){
std::cout << "Connection Error: " << mysql_error(connection) << std::endl;
exit(1);
}
return connection;
}
// mysql_res = mysql result
MYSQL_RES* mysql_perform_query(MYSQL *connection, const char *sql_query){
//send query to db
if(mysql_query(connection, sql_query)){
std::cout << "MySQL Query Error: " << mysql_error(connection) << std::endl;
exit(1);
}
return mysql_use_result(connection);
}
int main(int argc, char const *argv[])
{
MYSQL *con; // the connection
MYSQL_RES *res; // the results
MYSQL_ROW row; // the results row (line by line)
struct connection_details mysqlD;
mysqlD.server = "localhost"; // where the mysql database is
mysqlD.user = "netser"; // the root user of mysql
mysqlD.password = "root"; // the password of the root user in mysql
mysqlD.database = "mydatabase"; // the databse to pick
// connect to the mysql database
con = mysql_connection_setup(mysqlD);
// assign the results return to the MYSQL_RES pointer
res = mysql_perform_query(con, "show tables");
std::cout << ("MySQL Tables in mysql database:") << std::endl;
while ((row = mysql_fetch_row(res)) !=NULL)
std::cout << row[0] << std::endl;
/* clean up the database result set */
mysql_free_result(res);
/* clean up the database link */
mysql_close(con);
return 0;
}
When I try to compile it using:
g++ connectdb.cpp -o output && ./output
I get the next few errors:
/usr/bin/ld: /tmp/ccDwpmw3.o: in function `mysql_connection_setup(connection_details)':
connectdb.cpp:(.text+0xf): undefined reference to `mysql_init'
/usr/bin/ld: connectdb.cpp:(.text+0x3c): undefined reference to `mysql_real_connect'
/usr/bin/ld: connectdb.cpp:(.text+0x6c): undefined reference to `mysql_error'
/usr/bin/ld: /tmp/ccDwpmw3.o: in function `mysql_perform_query(st_mysql*, char const*)':
connectdb.cpp:(.text+0xc4): undefined reference to `mysql_query'
/usr/bin/ld: connectdb.cpp:(.text+0xef): undefined reference to `mysql_error'
/usr/bin/ld: connectdb.cpp:(.text+0x125): undefined reference to `mysql_use_result'
/usr/bin/ld: /tmp/ccDwpmw3.o: in function `main':
connectdb.cpp:(.text+0x1ca): undefined reference to `mysql_fetch_row'
/usr/bin/ld: connectdb.cpp:(.text+0x213): undefined reference to `mysql_free_result'
/usr/bin/ld: connectdb.cpp:(.text+0x21f): undefined reference to `mysql_close'
{By the way, I use Parrot OS with Mariadb and use VSCode}
I have never worked with databases in C++ before, so I have barely any idea what could be the problem, but I can assure you that the database does exit and that the connection to mysql.h has no problems...

Answer 1

The problem was how I was executing it, I had to use
g++ connectdb.cpp -o output -L/usr/include/mariadb/mysql -lmariadbclient
And not
g++ connectdb.cpp -o output
For future people with the same problem, here's a breakdown:
g++ connectdb.cpp -o output (normal compile)
-L/usr/include/mariadb/mysql (depending on what OS you have and if you use mariadb, you may have to change this to something like -L/usr/include/mysql instead, if you do use mariadb and still have a problem, remember to apt-get install libmariadb-dev)
-lmariadbclient (You have to apt-get install mariadb... If you're using MySQL, use -lmysqlclient instead)