MySQL-如果在其他表中出现超过x次,则选择行 [英] MySQL - Select row if appear more than x times in other table
问题描述
让我们说我有两个表,成员"和订单"具有1:N的关系:
Lets say I have two tables, Members and Orders with a 1:N relation:
Members | Orders
UserID Name | OrderID UserID Name
111 Peter | 777 111 Peter
222 Bart | 888 333 Joe
333 Joe | 999 111 Peter
444 Andrew | 101 444 Andrew
| 102 111 Peter
| 103 333 Joe
如果会员在订单"表中有多个订单,我正在尝试从会员"表中获取会员ID".
I am trying to get the Members ID from the Members table, in case that Member has more than 1 order in the Orders table.
所以结果应该是...
So the result should be...
Members
UserID Name
111 Peter
333 Joe
...因为彼得和乔在订单"表中都至少有2个订单.
...because Peter and Joe both have at least 2 orders in the Orders table.
我试图得到以下结果:
SELECT
s.UserID,
FROM Members s
INNER JOIN Orders o
ON s.UserID = o.UserID
WHERE
s.UserID IN
(
SELECT UserID
FROM Orders
GROUP BY UserID
HAVING COUNT(*) > 5
)
但是那给了我Peter 3次,Joe 2次.所以我得到重复而不是每个UserID一次.如何获得没有重复的结果?
But that gives me Peter back 3 times, and Joe 2 times; so I get duplicates instead of each UserID once. How can I get the result without duplicates?
推荐答案
我假设(并希望)您没有两次存储用户名,因为这会在用户更改名称时导致数据质量问题.
I'm assuming (and hoping) that you're not storing the user's name twice, since that leads to data quality issues when the user changes their name.
假设表格的结构如下:
CREATE TABLE
Members
(
UserID INT,
Name VARCHAR(15)
);
INSERT INTO
Members
VALUES
(111, 'Peter'),
(222, 'Bart'),
(333, 'Joe'),
(444, 'Andrew');
CREATE TABLE
Orders
(
OrderID INT,
UserID INT
);
INSERT INTO
Orders
VALUES
(777, 111),
(888, 333),
(999, 111),
(101, 444),
(102, 111),
(103, 333);
您可以使用GROUP BY
和HAVING
子句,该子句将为您提供具有1个以上(或选择的任何数量)订单的所有用户的UserID
.然后,将其连接到Members
表以获取名称.
You can use a GROUP BY
and HAVING
clause which would give you the UserID
of all users with more than 1 (or whichever number you choose) orders. Then, you join that to the Members
table to get the name.
SELECT
Orders.UserID,
Members.Name
FROM
Orders
INNER JOIN
Members
ON Orders.UserID = Members.UserID
GROUP BY
UserID,
Members.Name
HAVING
COUNT(OrderID) > 1;
SQLFiddle: http://sqlfiddle.com/#!9/1dadc4/2
SQLFiddle: http://sqlfiddle.com/#!9/1dadc4/2
但是,如果您已经存储了名称(并且没有更改),则可以跳过JOIN
,如下所示:
However, if you already have the names stored (and that's not changing), then you could skip the JOIN
like below:
SELECT
UserID,
Name
FROM
Orders
GROUP BY
UserID,
Name
HAVING
COUNT(OrderID) > 1
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