PolarDB:Database connection

First, add the dependency of the MySQL JDBC driver to the pom.xml file. Sample code:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.27</version>
</dependency>

Connect to the cluster. Replace the <HOST>, port number, <USER>, <PASSWORD>, <DATABASE>, <YOUR_TABLE_NAME>, and <YOUR_TABLE_COLUMN_NAME> with the information of your database.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class DatabaseConnection {
   public DatabaseConnection() {
   }

   public static void main(String[] args) {
      // The endpoint, port, and database name of the PolarDB cluster to be connected.
      String url = "jdbc:mysql://<HOST>:3306/<DATABASE>?useSSL=false&serverTimezone=UTC";
      // The database account.
      String user = "<USER>";
      // The password of the database account.
      String password = "<PASSWORD>";

      try {
         Class.forName("com.mysql.cj.jdbc.Driver");
         Connection conn = DriverManager.getConnection(url, user, password);
         Statement stmt = conn.createStatement();
         // The name of the data table to be queried.
         ResultSet rs = stmt.executeQuery("SELECT * FROM `<YOUR_TABLE_NAME>`");

         while(rs.next()) {
            // The column name of the data table to be queried.
            System.out.println(rs.getString("<YOUR_TABLE_COLUMN_NAME>"));
         }

         rs.close();
         stmt.close();
         conn.close();
      } catch (Exception var7) {
         var7.printStackTrace();
      }

   }
}

First, install the PyMySQL library. You can run the following command to install it:

pip3 install PyMySQL

Connect to the cluster. Replace the <HOST>, port number, <USER>, <PASSWORD>, <DATABASE>, and <YOUR_TABLE_NAME> with the information of your database.

import pymysql

# The database connection parameters.
host = '<HOST>' # The endpoint of the PolarDB cluster.
port = 3306 # The default port 3306
user = '<USER>' # The database account.
password = '<PASSWORD>' # The password of the database account.
database = '<DATABASE>' # The name of the database to be connected.

try:
    # Establish a database connection.
    connection = pymysql.connect(
        host=host,
        port=port,
        user=user,
        passwd=password,
        db=database
    )

    # Obtain the cursor.
    with connection.cursor() as cursor:
        # Execute an SQL query.
        sql = "SELECT * FROM '<YOUR_TABLE_NAME>'" # The name of the table to be queried.
        cursor.execute(sql)

        # Obtain the query result.
        results = cursor.fetchall()
        for row in results:
            print(row)

finally:
    # Close the database connection.
    if 'connection' in locals() and connection.open:
        connection.close()

First, install the go-sql-driver/mysql driver. You can run the following command to install the driver:

go get -u github.com/go-sql-driver/mysql

Connect to the cluster. Replace the <HOST>, port number, <USER>, <PASSWORD>, <DATABASE>, and <YOUR_TABLE_NAME> with the information of your database.

package main

import (
    "database/sql"
    "fmt"
    "log"
    _ "github.com/go-sql-driver/mysql"
)

func main() {
    // Database connection parameters.
    dbHost := "<HOST>" // The endpoint of the PolarDB cluster.
    dbPort := "3306" // The default port 3306.
    dbUser := "<USER>" // The database account.
    dbPass := "<PASSWORD>" // The password of the database account.
    dbName := "<DATABASE>" // The name of the database to be connected.

    // Build DSN (Data Source Name)
    dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local", dbUser, dbPass, dbHost, dbPort, dbName)

    // Create a database connection.
    db, err := sql.Open("mysql", dsn)
    if err != nil {
        log.Fatalf("Failed to connect to database: %v", err)
    }
    defer db.Close()

    // Test the connection.
    err = db.Ping()
    if err != nil {
        log.Fatalf("Failed to ping database: %v", err)
    }

    // Create a cursor.
    var result string
    err = db.QueryRow("SELECT VERSION()").Scan(&result)
    if err != nil {
        log.Fatalf("Failed to execute query: %v", err)
    }

    // Print the database version.
    fmt.Printf("Connected to database, version: %s\n", result)

    // Execute an SQL query.
    rows, err := db.Query("SELECT * FROM '<YOUR_TABLE_NAME>'") // The name of the data table that is queried.
    if err != nil {
        log.Fatalf("Failed to execute query: %v", err)
    }
    defer rows.Close()