MYSQL帮助，如何计算结果

Question

运行此sql：

SELECT
    user_id,
    base_item
FROM
    items
WHERE
    base_item = "202"

但是，给我这个http://prntscr.com/9gwwxq，如何扩展MYSQL查询，以将user_id具有的202个base_items的数量相加。例如user_id 41有6。

Answer 1

试一试：

SELECT
    user_id,
    count(base_item) as c
FROM
    items
WHERE
    base_item = "202"
group by
    user_id

Answer 2

这将为每个用户ID提供“202”base_items的编号：

SELECT
    user_id,
    COUNT(*)
FROM
    items
WHERE
    base_item = "202"
GROUP BY user_id

Answer 3

试试这个类似的count of base_item

SELECT
    user_id, 
    base_item, count(*) as user_no
FROM
    items
WHERE
    base_item = "202" 
GROUP BY user_id