sql - 如何在 SQL Server 中更新具有多个组合行的行

Question

我有两张表如下所述：

Table1

id | table2_id | value
1  | 1         | AAA
2  | 1         | BBB
3  | 1         | CCC

Table2

id | value
1  | XXXX

并且我想Table2使用来自的组合值进行更新Table1。

输出预期Table2

id | value
1  | AAA,BBB,CCC

我该怎么做或者有最好的方法来获得上面解释的预期结果，只是在 sql server 中使用 TSQL？

Answer 1

你可以用Common Table Expression这个，

WITH record
AS
(
    SELECT [table2_id],
            STUFF((SELECT ',' + [value]
                    FROM Table1
                    WHERE [table2_id] = a.[table2_id]
                    FOR XML PATH ('')), 1, 1, '')  AS val_list
    FROM    Table1 AS a
    GROUP   BY [table2_id]
)
UPDATE  a
SET     a.value = b.val_list
FROM    table2 a
        INNER JOIN record b
            ON a.ID = b.table2_id

• SQLFiddle 演示

Answer 2

在探索了 JW 웃</a> 答案后，我修改并执行了最简单的方法，如下查询：

UPDATE table2
SET table2.value = STUFF((SELECT ',' + [value]
                        FROM Table1
                        WHERE [table2_id] = a.[table2_id]
                        FOR XML PATH ('')), 1, 1, '')
FROM Table1 a 
WHERE table2.ID = a.table2_id

在SQLFiddle 演示这里