GROUP_CONCAT在组合商品中的使用

表：combined_product_item

-------------------------
pid sku quality
-------------------------
1 sku1 1
1 sku2 3
1 sku3 2
2 sku1 3
--------------------------

SELECT
    (
        GROUP_CONCAT(
            CONCAT_WS('*', sku, quantity) SEPARATOR '+'
        )
    ) AS relation
FROM
    combined_product_item
GROUP BY
    pid;

结果：

relation
--------
sku1*1+sku2*3+sku3*2
sku1*3