mysql两条数据合并

UPDATE your_table
SET combined_field = CASE
    WHEN condition1 THEN field1
    WHEN condition2 THEN field2
    -- ...
END
WHERE ...;

-- 创建示例表
CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(255),
    phone VARCHAR(255),
    email VARCHAR(255)
);

-- 插入示例数据
INSERT INTO users (id, name, phone, email) VALUES
(1, 'Alice', '123456789', 'alice@example.com'),
(1, 'Alice', NULL, 'alice.work@example.com'),
(2, 'Bob', '987654321', NULL);

-- 使用UPDATE语句合并联系方式
UPDATE users
SET contact_info = CONCAT_WS(';', COALESCE(phone, ''), COALESCE(email, ''))
WHERE id IN (SELECT id FROM users GROUP BY id HAVING COUNT(*) > 1);

-- 删除重复记录（保留合并后的记录）
DELETE u1 FROM users u1
JOIN users u2 ON u1.id = u2.id AND u1.phone = u2.phone AND u1.email = u2.email
WHERE u1.id > u2.id;