Question

使用Microsoft SQL Server Management Studio - SQL Server数据库。

我有两张桌子 - 第一张桌子是我们所有客户的桌子。第二个表，即我尝试加入的表，是一个包含客户档案的所有更改的表。

我想要的是最早的date_changed，以及与该记录相关联的信息，为每个客户提供。

特定客户端的客户端表包含：

client_code | first_name | last_name | zip_postal_code
------------|------------|-----------|----------------
168187      | Trees      | Karoline  | n

此客户的更改表包含许多记录：

client_code | clerk_changed | date_changed
------------|---------------|------------------------
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | taranab       | 2017-03-18 10:37:00.000
168187      | saml          | 2017-04-21 09:36:00.000
168187      | matijay       | 2017-04-22 06:22:00.000

运行查询：

SELECT client.client_code, client.first_name, client.last_name, client.zip_postal_code, clerk.clerk_changed, clerk.date_changed
FROM maclient client
LEFT JOIN (
    SELECT MIN(date_changed) AS 'date_changed', client_code, clerk_changed
    FROM maclntchg
    GROUP BY client_code, clerk_changed
) AS clerk ON client.client_code = clerk.client_code
WHERE client.client_code > '104' AND ((client.country_code = 'ca' AND LEN(client.zip_postal_code) <> 7) OR (client.country_code = 'us' AND LEN(client.zip_postal_code) <> 5)) AND client.zip_postal_code <> 'N/A' AND client.client_code = '168187'
ORDER BY clerk.clerk_changed, clerk.date_changed, client.last_name

返回：

client_code | first_name | last_name | zip_postal_code | clerk_changed | date_changed
------------|------------|-----------|-----------------|---------------|------------------------
168187      | Trees      | Karoline  | n               | matijay       | 2017-04-22 06:22:00.000
168187      | Trees      | Karoline  | n               | saml          | 2017-04-21 09:36:00.000
168187      | Trees      | Karoline  | n               | taranab       | 2017-03-18 10:37:00.000

而不是预期的结果：

client_code | first_name | last_name | zip_postal_code | clerk_changed | date_changed
------------|------------|-----------|-----------------|---------------|------------------------
168187      | Trees      | Karoline  | n               | taranab       | 2017-03-18 10:37:00.000

Answer 1

SELECT client.client_code, client.first_name, client.last_name, client.zip_postal_code, clerk.clerk_changed, clerk.date_changed
FROM maclient client
OUTER APPLY (
    SELECT TOP 1 date_changed AS 'date_changed', client_code, clerk_changed
    FROM maclntchg clerk
    WHERE client.client_code = clerk.client_code
    ORDER BY date_changed ASC
) 
WHERE client.client_code > '104' AND ((client.country_code = 'ca' AND LEN(client.zip_postal_code) <> 7) OR (client.country_code = 'us' AND LEN(client.zip_postal_code) <> 5)) AND client.zip_postal_code <> 'N/A' AND client.client_code = '168187'
ORDER BY clerk.clerk_changed, clerk.date_changed, client.last_name

另一个：

SELECT client.client_code, client.first_name, client.last_name, client.zip_postal_code, clerk.clerk_changed, clerk.date_changed
FROM maclient client
LEFT JOIN (
    SELECT ROW_NUMBER() OVER(PARTITION BY client_code ORDER BY date_changed ASC) row_num, date_changed AS 'date_changed', client_code, clerk_changed
    FROM maclntchg 
) clerk ON client.client_code = clerk.client_code AND clerk.row_num = 1
WHERE client.client_code > '104' AND ((client.country_code = 'ca' AND LEN(client.zip_postal_code) <> 7) OR (client.country_code = 'us' AND LEN(client.zip_postal_code) <> 5)) AND client.zip_postal_code <> 'N/A' AND client.client_code = '168187'
ORDER BY clerk.clerk_changed, clerk.date_changed, client.last_name

仅从连接表返回第一个日期行

1 个答案: