Question

任何人都可以帮我完成这项任务吗？我们说我有两张桌子：

_表1＆＃34;发布者＆＃34;：ASIN，Price，publisher_ID

_表2＆＃34;违规＆＃34;：ASIN，publisher_ID，Previous_Violations（Y / N），ID

现在我有了这个

    SET @PUB = "

    'A','B','C','D',

    " 
    SELECT p.publisher_ID, count(distinct v.id) as "Number of Violations"
    FROM Publisher p
    LEFT JOIN Violations v
    ON p.publisher_ID = v.publisher_ID
    and p.Previous_Violations = 'Y'

    WHERE 
    p.publisher_ID IN (",@PUB,")
    GROUP BY p.publisher_ID

我想查看@PUB列表中所有发布者的历史记录违规行为。所以会有4个案例：

@PUB中的所有发布商都存在两个表格
表1中存在@PUB中的发布者，但不是2。
表2中存在@PUB中的发布者，但不是1.
@PUB中的发布商并不存在于2个表中的任何一个中。

为了澄清，让我们说酒吧A＆amp; B存在于两个表中，C存在于表1中（不是2），D存在于表2中（但不存在于1中），并且E也不存在于表中。

现在我上面的查询仅给出（由于左连接）

A 3

B 2

C 4

但我希望它显示：

A 3

B 2

C 4

D 6

E Null

Answer 1

如果您没有大型列表，可以尝试以下操作，您可以创建一个为您生成查询的过程

(
    SELECT p.publisher_ID, sum(IF(v.Previous_Violations = 'Y', 1, 0)) AS "Number of Violations"
    FROM (SELECT 'A' AS publisher_ID) AS p LEFT JOIN Violations v USING(publisher_ID) 
    GROUP BY p.publisher_ID
)
UNION
(
     SELECT p.publisher_ID, sum(IF(v.Previous_Violations = 'Y', 1, 0)) AS "Number of Violations"
    FROM (SELECT 'B' AS publisher_ID) AS p LEFT JOIN Violations v USING(publisher_ID) 
    GROUP BY p.publisher_ID)
UNION
(
     SELECT p.publisher_ID, sum(IF(v.Previous_Violations = 'Y', 1, 0)) AS "Number of Violations"
    FROM (SELECT 'C' AS publisher_ID) AS p LEFT JOIN Violations v USING(publisher_ID) 
    GROUP BY p.publisher_ID)
UNION
(
     SELECT p.publisher_ID, sum(IF(v.Previous_Violations = 'Y', 1, 0)) AS "Number of Violations"
    FROM (SELECT 'D' AS publisher_ID) AS p LEFT JOIN Violations v USING(publisher_ID) 
    GROUP BY p.publisher_ID
)
UNION
(
     SELECT p.publisher_ID, sum(IF(v.Previous_Violations = 'Y', 1, 0)) AS "Number of Violations"
    FROM (SELECT 'E' AS publisher_ID) AS p LEFT JOIN Violations v USING(publisher_ID) 
    GROUP BY p.publisher_ID
)

即使不在联合表

1 个答案: