Lindorm:Use C API to develop applications

Prerequisites

• The MySQL compatibility feature is enabled for the instance. For more information, see Enable the MySQL compatibility feature.

• The IP address of your client is added to the whitelist of your Lindorm instance. For more information, see Configure a whitelist.

Procedure

1. Install the dependency of C API for MySQL. The following command provides an example on how to install the dependency of C API for MySQL in CentOS:

yum install mysql-devel

2. Configure connection parameters.

   char lindorm_addr[] = "ld-uf6k8yqb741t3****-proxy-sql-lindorm-public.lindorm.rds.aliyuncs.com";
   char lindorm_user[] = "user";
   char lindorm_password[] = "test";
   char database[] = "default";
   int lindorm_mysql_port = 33060;

   Parameters

   Parameter	Description
   lindorm_addr	The LindormTable endpoint for MySQL. For more information about how to obtain it, see View endpoints. Important If your application is deployed on an ECS instance, we recommend that you use a VPC to connect to the Lindorm instance to ensure higher security and lower network latency. If your application is deployed on-premises, enable public network access in the console before connecting to the Lindorm instance over the public network. To do this, in the console, choose Database Connections > Wide Table Engine. On the Wide Table Engine tab, click Enable Public Endpoint. To access a Lindorm instance from a virtual private cloud (VPC), set lindorm_addr to the MySQL-compatible VPC address. To access a Lindorm instance from the public network, set lindorm_addr to the MySQL-compatible Internet address.
   lindorm_user	If you forget your password, you can change the password in the cluster management system of LindormTable. For more information, see Manage users.
   lindorm_password
   database	The name of the database to which you want to connect. By default, your client is connected to a database named default.
   lindorm_mysql_port	The port used to access LindormTable using MySQL. The value of this parameter is fixed to 33060.

3. You can create a connection to LindormTable to use the wide table SQL syntax. The following example shows how to create a table.

       // Create a connection.
       if (!mysql_real_connect(&conn,lindorm_addr,lindorm_user,lindorm_password,database,lindorm_mysql_port,NULL,0)) {
           printf("Failed to connect to database: Error: %s\n",
                   mysql_error(&conn));
           exit(1);
       } else {
           printf("conect lindorm successfully\n");
       }
   
   
       // Create a table.
       char create_table[] = "create table if not exists user_test(id int, name varchar,age int, primary key(id))";
       res = mysql_query(&conn, create_table);
       if (!res) {
           printf("create table successfully\n");
       } else {
           printf("create table Error: %s\n", mysql_error(&conn));
           exit(1);
       }

4. To compile the code in the demo.c file, execute the following command.

   gcc -o a.out $(mysql_config --cflags) demo.c $(mysql_config --libs)
   ./a.out

Complete example

The following shows the complete sample code:

#include <stdio.h>
#include "mysql/mysql.h"
int main(){
    MYSQL conn;
    int res;
    MYSQL_RES * result;
    MYSQL_ROW row;
    mysql_init(&conn);

    // Connection configuration.
    char lindorm_addr[] = "ld-uf6k8yqb741t3****-proxy-sql-lindorm-public.lindorm.rds.aliyuncs.com"; // LindormTable endpoint for MySQL
    char lindorm_user[] = "user"; // Username for LindormTable
    char lindorm_password[] = "test"; // Password for LindormTable
    char database[] = "default"; // Database name to connect to
    int lindorm_mysql_port = 33060; // MySQL protocol port for LindormTable (fixed at 33060)

    // Create a connection.
    if (!mysql_real_connect(&conn,lindorm_addr,lindorm_user,lindorm_password,database,lindorm_mysql_port,NULL,0)) {
        printf("Failed to connect to database: Error: %s\n",
                mysql_error(&conn));
        exit(1);
    } else {
        printf("conect lindorm successfully\n");
    }


    // Create a table.
    char create_table[] = "create table if not exists user_test(id int, name varchar,age int, primary key(id))";
    res = mysql_query(&conn, create_table);
    if (!res) {
        printf("create table successfully\n");
    } else {
        printf("create table Error: %s\n", mysql_error(&conn));
        exit(1);
    }

    // Insert data.
    char insert_data[] = "upsert into user_test(id,name,age) values(3,'wangwu',23)";
    res = mysql_query(&conn, insert_data);
    if (!res) {
        printf("insert data successfully\n");
    } else {
        printf("insert data Error: %s\n", mysql_error(&conn));
        exit(1);
    }

    // Query data.
    char select_query[] = "select * from user_test";
    if (mysql_query(&conn, select_query) != 0) {
        printf("select Error: %s\n", mysql_error(&conn));
        exit(1);
    } else {
        if ((result = mysql_store_result(&conn)) == NULL) {
            printf("store result Error: %s\n", mysql_error(&conn));
            exit(1);
        }
        else {
            while ((row = mysql_fetch_row(result)) != NULL) {
                printf("name is %s , ", row[0]);
                printf("age is %s\n", row[1]);
            }
        }
    }

    return 0;
}

The following result is returned:

conect lindorm successfully
create table successfully
insert data successfully
name is 3 , age is wangwu