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 whitelists.

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 the LindormTable endpoint for MySQL, 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 a local server and needs to connect to the Lindorm instance over the Internet, you can perform the following steps to enable the Internet endpoint for the instance in the Lindorm console: In the left-side navigation pane, select Database Connections > Wide Table Engine. On the Wide Table Engine tab, click Enable Public Endpoint. If you use a VPC to access the Lindorm instance, specify the LindormTable VPC endpoint for MySQL in the value of lindorm_addr. If you use the Internet to access the Lindorm instance, specify the LindormTable Internet endpoint for MySQL in the value of lindorm_addr.
   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 by using MySQL. The value of this parameter is fixed to 33060.

3. Establish a connection and use LindormTable SQL to perform operations in LindormTable. The following code block provides an example on how to use LindormTable SQL to create a table:

       // Establish 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. If the code is saved in the demo.c file, run the following command to compile the code:

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

Sample code

The following code provides a complete example on how to connect to and use LindormTable by using C API for MySQL:

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

    // Configure connection parameters.
    char lindorm_addr[] = "ld-uf6k8yqb741t3****-proxy-sql-lindorm-public.lindorm.rds.aliyuncs.com"; // Specify the LindormTable endpoint for MySQL.
    char lindorm_user[] = "user"; // Specify the username used to connect to LindormTable.
    char lindorm_password[] = "test"; // Specify the password used to connect to LindormTable.
    char database[] = "default"; // Specify the database that you want to connect.
    int lindorm_mysql_port = 33060; // Specify the port used to access LindormTable by using MySQL. The value of this parameter is fixed to 33060.

    // Establish 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 to the table.
    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 in the table.
    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