Question

我有2个表，例如：

表1

ID,Name,Address1

表2

Visit_date,item,id

表2记录了大量访问次数，以及地址的ID。

我想编写一个查询，选择所有姓名和地址及其最后访问日期和项目。

SELECT * 
FROM (SELECT ID, NAME, ADDRESS FROM table1) as temp 
RIGHT JOIN table2 ON table1.ID = temp.ID;

到目前为止我已经到了。

Answer 1

您可以在CTE中使用ROW_NUMBER。

;WITH cte AS (
    SELECT t1.name, t1.address1, t2.Visit_date, t2.item, 
        ROW_NUMBER() OVER (PARTITION BY t2.id ORDER BY t2.visit_date DESC) AS rn
FROM table2 t2
INNER JOIN table1 t1
    ON t1.id = t2.id
)
SELECT name, address1, visit_date, item
FROM cte
WHERE rn = 1

SQLFiddle proof

Answer 2

这可能是cross-apply

的情况

select T1.ID, T1.Name, T1.Address1, T2.item, T2.Visit_date from
Table1 T1 cross apply (select top 1 * from Table2 where ID = Table1.ID 
order by     Visit_date desc) T2

使用JOIN获取最近的事件

2 个答案: