如何在 SQL 中不包含重复行？

Question

我的 schemea 是一个客户 table，他使用地址加入 table。有些地址有两个：账单和送货。

如何通过开票或送货让每条线有一个客户。

我觉得应该使用 DISTINCT，但如果我这样做，它会删除附有账单和送货地址的我的客户。

enter image description here

SELECT
    Firstname,
    LastName,
    Line1,
    City,
    State,
    ZipCode,
FROM
    Customers as c
    INNER JOIN Addresses as a ON c.CustomerID = a.CustomerID
ORDER BY
    c.CustomerID

Answer 1

使用 row_number()over() 和常见的 table 表达式，您可以为每个客户 select table Addresses 的第一行。然后将 table 与客户 table 连接起来，每个客户只有一行。

with addess as 
(
  select *,row_number()over(partition by customerid order by addressid)rn from Addresses 
)
SELECT
    Firstname,
    LastName,
    Line1,
    City,
    State,
    ZipCode,
FROM
    Customers as c
    INNER JOIN Address as a ON c.CustomerID = a.CustomerID and rn=1
ORDER BY
    c.CustomerID

一个较慢的子查询解决方案：

SELECT
    Firstname,
    LastName,
    Line1,
    City,
    State,
    ZipCode,
FROM
    Customers as c
    INNER JOIN Address as a ON c.CustomerID = a.CustomerID and 
    a.AddressID=(select min(addressid) from Addresses where CustomerID=c.CustomerID)
ORDER BY
    c.CustomerID

如何在 SQL 中不包含重复行？

how to NOT have repeating rows in SQL?

sql

sql-server

distinct