MySQL Connection In C
The C MySQL Connector is required for C to connect to the database.
A separate MariaDB C Connector is available and can be installed.
The MySQL header must be included first. This tutorial uses MariaDB 10.11.8 and GCC 14.2.1 on Fedora Linux 40.
MySQL Interface
| Name | Description | Example |
|---|---|---|
| mysql_real_connect | Create database connection | mysql_real_connect(conn, hostname, dbuser, dbpass, dbname) |
| execute | Perform database query | execute(query) |
| mysql_num_rows | Gets the number of rows in the result set | mysql_num_rows(MYSQL_RES *result) |
| Name | Description | Example |
Install MySQL Driver
dnf install mariadb-connector-c-devel
C MySQL Select Data
#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>
int main(void)
{
MYSQL *conn;
if ((conn = mysql_init(NULL)) == NULL)
{
fprintf(stderr, "Could not init DB\n");
return EXIT_FAILURE;
}
if (mysql_real_connect(conn, "localhost", "dbuser", "dbpass", "dbname", 0, NULL, 0) == NULL)
{
fprintf(stderr, "DB Connection Error\n");
return EXIT_FAILURE;
}
if (mysql_query(conn, "SELECT sid, name, age FROM Students") != 0)
{
fprintf(stderr, "Query Failure\n");
return EXIT_FAILURE;
}
MYSQL_RES *result = mysql_store_result(conn);
int num_fields = mysql_num_fields(result);
MYSQL_ROW row;
while ((row = mysql_fetch_row(result)))
{
for(int i = 0; i < num_fields; i++)
{
printf("%s ", row[i] ? row[i] : "NULL");
}
printf("\n");
}
mysql_free_result(result);
mysql_close(conn);
return EXIT_SUCCESS;
}
SQL Injection Security Warning
Variable input must be sanitized, validated, properly formatted and escaped. For this tutorial, the variable input is known and trusted and security is not concerning.
C MySQL Select Data Escape String
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <mysql/mysql.h>
int main(void)
{
MYSQL *conn;
if ((conn = mysql_init(NULL)) == NULL)
{
fprintf(stderr, "Could not init DB\n");
return EXIT_FAILURE;
}
if (mysql_real_connect(conn, "localhost", "dbuser", "dbpass", "dbname", 0, NULL, 0) == NULL)
{
fprintf(stderr, "DB Connection Error\n");
return EXIT_FAILURE;
}
char from[100];
char to[100];
char query[1000];
sprintf(from, "D'Arcy");
mysql_escape_string(to, from, strlen(from));
sprintf(query, "SELECT sid, name, age FROM Students WHERE name = '%s'", to);
if (mysql_query(conn, query) != 0)
{
fprintf(stderr, "Query Failure\n");
return EXIT_FAILURE;
}
MYSQL_RES *result = mysql_store_result(conn);
int num_fields = mysql_num_fields(result);
MYSQL_ROW row;
while ((row = mysql_fetch_row(result)))
{
for(int i = 0; i < num_fields; i++)
{
printf("%s ", row[i] ? row[i] : "NULL");
}
printf("\n");
}
mysql_free_result(result);
mysql_close(conn);
return EXIT_SUCCESS;
}
Compile And Execute
gcc -o sql sql.c $(mariadb_config --include --libs) ./sql
Usage
You can use any IDE or text editor and the command line to compile and execute C code. In this tutorial, the OjamboShop.com Learning Python Course and Learning PHP completion inspired the database connection.
Open Source
GCC is licensed under the GNU General Public License version with the GCC Runtime Library Exception, version 3.1. This allows commercial use, modification, distribution, and allows making derivatives proprietary.
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Conclusion:
GCC makes it easy for C to perform database connections using the MySQL Connector. The MySQL header must be included in order to perform MySQL functions including the procedure to select database data.
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