mysql 判断数据变化

DELIMITER $$

CREATE TRIGGER after_data_change
AFTER UPDATE ON your_table
FOR EACH ROW
BEGIN
    IF OLD.column_name != NEW.column_name THEN
        -- 数据发生变化，执行相应的操作
        INSERT INTO change_log (table_name, column_name, old_value, new_value, change_time)
        VALUES ('your_table', 'column_name', OLD.column_name, NEW.column_name, NOW());
    END IF;
END$$

DELIMITER ;

CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(255),
    version INT DEFAULT 0
);

UPDATE users SET name = 'new_name', version = version + 1 WHERE id = 1;

SELECT * FROM users WHERE id = 1 AND version = current_version;

CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(255),
    last_modified TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

SELECT * FROM users WHERE id = 1 AND last_modified > last_checked_time;