此 SQL 查询中出了什么问题

Question

我正在尝试从 1 个表中获取购物车，只有 1 个条件，即下一个"购物车必须比具有相同id_user的任何订单更新"

SELECT pso.*
FROM lafrips_cart pso
WHERE pso.id_customer > 0 
AND pso.date_add > (SELECT MAX(pso2.date_add)
FROM lafrips_orders pso2
WHERE pso2.id_customer < pso.id_customer)

我只是比较 2 个字段（pso.date_add 与 ps2.date_add）都是具有相同结构的日期时间

Answer 1

SELECT pso.*
FROM lafrips_cart pso
WHERE 
    pso.id_customer > 0 
    AND pso.date_add > (
        SELECT MAX(pso2.date_add)
        FROM lafrips_orders pso2
        WHERE pso2.id_customer = pso.id_customer
        )

Answer 2

正如你都说@Siyual和@Sergio">"是错误，实际上我觉得我像砖头一样厚，我可能要多睡几个小时

SELECT pso.*
FROM lafrips_cart pso
WHERE
pso.id_customer > 0 
AND pso.date_add > (
    SELECT MAX(pso2.date_add)
    FROM lafrips_orders pso2
    WHERE pso2.id_customer **=** pso.id_customer
    )

标有 ** 的 = 符号已替换