Question

我有一个表交易，我试图找出给定月份的新客户。这意味着如果客户在月份之前没有交易，他/她将被视为新客户。

我找到了一种方法，但它效率很低，需要很长时间。然后我遇到了这个比较不同方法的artikel。我试图将这种方法调整到我的方法而没有成功。

想象我的问题：

|--------------------------- time period with all transactions -----------------------|
|----- period before month transactions = 0) ---|---- curr month transactions > 0 ----|

表格如下：

transactions
id, email, state, date_paid

我的查询：

SELECT
    l.email
FROM
    transactions as l
LEFT JOIN transactions as r ON r.email = l.email
WHERE
    r.email IS NULL
AND l.state = 'paid'
AND r.state = 'paid'
AND l.date_paid <= '2013-12-31 23:59:59'
AND r.date_paid < '2013-12-01 00:00:00'

我做错了什么？

Answer 1

试试这个：

SELECT l.email
FROM transactions AS l
LEFT JOIN transactions AS r ON r.email = l.email AND r.state = 'paid' AND r.date_paid < '2013-12-01 00:00:00'
WHERE r.email IS NULL AND l.state = 'paid' AND l.date_paid <= '2013-12-31 23:59:59'

Answer 2

试试这个：

SELECT l.email
FROM transactions l
WHERE NOT l.email IN (SELECT r.email 
                      FROM transactions r
                      WHERE r.state = 'paid' AND r.date_paid < '2013-12-01 00:00:00')
      AND l.state = 'paid' AND l.date_paid <= '2013-12-31 23:59:59'

mysql查询内部连接在同一个表上具有不同条件

2 个答案: