MySQL中ON DUPLICATE KEY UPDATE优雅解决存在更新/不存在插入难题

INSERT INTO table_name (column1, column2, ..., columnN)
VALUES (value1, value2, ..., valueN)
ON DUPLICATE KEY UPDATE
    column1 = value1,
    column2 = value2,
    ...;

INSERT INTO table_name (column1, column2, ..., columnN)
VALUES (value1, value2, ..., valueN)
ON DUPLICATE KEY UPDATE
    column1 = VALUES(column1),
    column2 = VALUES(column2),
    ...;

INSERT INTO article_views (article_id, view_count) 
VALUES (123, 1) 
ON DUPLICATE KEY UPDATE 
	view_count = view_count + 1;

INSERT INTO system_config (config_key, config_value, last_updated) 
VALUES ('site_title', 'My Website', NOW()) 
ON DUPLICATE KEY UPDATE 
	config_value = VALUES(config_value), last_updated = NOW();

INSERT INTO shopping_cart (user_id, product_id, quantity) 
VALUES (123, 456, 2)
ON DUPLICATE KEY UPDATE 
    quantity = quantity + VALUES(quantity),
    added_at = CURRENT_TIMESTAMP;

-- 这个例子只在新的价格更低时才更新价格
INSERT INTO products (product_id, price, last_updated) 
VALUES (101, 99.99, NOW()) 
ON DUPLICATE KEY UPDATE 
    price = IF(VALUES(price) < price, VALUES(price), price),
    last_updated = NOW();

INSERT INTO user_stats (user_id, login_count) 
SELECT 123, 1 FROM dual
WHERE NOT EXISTS (SELECT 1 FROM users WHERE id = 123)
ON DUPLICATE KEY UPDATE 
	login_count = login_count + 1;

INSERT INTO log_entries (user_id, action, timestamp) 
VALUES 
    (1, 'login', NOW()),
    (2, 'view', NOW()),
    (3, 'purchase', NOW())
ON DUPLICATE KEY UPDATE 
    action = VALUES(action), 
    timestamp = VALUES(timestamp);

REPLACE INTO users (email, name, login_count) 
VALUES ('test@example.com', 'Test User', 1);

INSERT IGNORE INTO users (email, name) 
VALUES ('test@example.com', 'Test User');