题解 | 商品销售总额分布

SELECT
    CASE 
        WHEN u.pay_method = '' THEN 'error'
        ELSE u.pay_method
    END AS pay_method,
    COUNT(*) as count
FROM
    user_client_log u 
    JOIN product_info p ON u.product_id=p.product_id
WHERE
    p.product_name='anta' AND u.step='select'
GROUP BY
    u.pay_method 
ORDER BY
    count DESC

在select中也可以用case when语句

CASE

WHEN u.pay_method = '' THEN 'error'

ELSE u.pay_method

END AS pay_method,