代码片段仓库

-- 获取用户及其订单信息
SELECT 
    u.id AS user_id,
    u.name AS user_name,
    o.id AS order_id,
    o.amount,
    o.order_date
FROM 
    users u
JOIN 
    orders o ON u.id = o.user_id
WHERE 
    u.status = 'active'
ORDER BY 
    o.order_date DESC;

let db;
let request = indexedDB.open('myDatabase', 1);
request.onerror = (event) => {
  console.error('DB error', event.target.error);
};
request.onsuccess = (event) => {
  db = event.target.result;
};
request.onupgradeneeded = (event) => {
  db = event.target.result;
  if (!db.objectStoreNames.contains('store')) {
    db.createObjectStore('store', { keyPath: 'id' });
  }
};

CREATE TABLE USERS (
  id INT PRIMARY KEY AUTO_INCREMENT,
  username VARCHAR(255) NOT NULL,
  email VARCHAR(255) NOT NULL,
  password VARCHAR(255) NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  URIQUE (username),
  URIQUE (email)
);

import sqlite3

def sqlite_demo():
    conn = sqlite3.connect('mydb.db')
    cur = conn.cursor()
    
    # Create table
    cur.execute('''
        CREATE TABLE IF NOT EXISTS USERS (id INTEGER PRIMARY KEY, 
                            name TEXT NOT NULL,
                            email TEXT NOT NULL)
    ''')
    
    # Insert data
    cur.execute("INSERT INTO USERS (name, email) VALUES (?, ?)", ('John Doe', 'john@example.com'))
    
    # Query data
    cur.execute("SELECT * FROM USERS")
    print(cur.fetchall())
    
    conn.commit()
    conn.close()

SELECT
  customer_id,
  order_date,
  RANK() OVER (

    PARTITION BY customer_id
    ORDER BY order_date DESC
  ) AS order_rank
FROM orders;

public class DbConnector {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydb";
        String user = "username";
        String password = "password";
        
        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            System.out.println("Connection succeeded!");
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}