sql-server - 创建一个存储过程来聚合行

Question

有一个包含以下行的事务表:

Id    UserId   PlatformId    TransactionTypeId
-------------------------------------------------
 0       1          3                1
 1       1          1                2
 2       2          3                2
 3       3          2                1
 4       2          3                1

如何编写一个存储过程，将行聚合到具有以下格式的新表中？

Id    UserId   Platforms          TransactionTypeId
-------------------------------------------------
 0      1      {"p3":1,"p1":1}    {"t1":1,"t2":1}
 1      2      {"p3":2}           {"t2":1,"t1":1}
 3      3      {"p2":1}           {"t1":1}

因此，行按用户分组，计算每个平台/交易类型并存储为键/值 json 字符串。

引用号:My previous related question

Answer 1

您可以使用GROUP BY和FOR JSON:

SELECT MIN(ID) AS ID, UserId, MIN(sub.x) AS Platforms, MIN(sub2.x) AS Transactions
FROM tab t
OUTER APPLY (SELECT CONCAT('p', platformId) AS platform, cnt 
            FROM (SELECT PlatformId, COUNT(*) AS cnt
                  FROM tab t2 WHERE t2.UserId = t.UserId  
                  GROUP BY PlatformId) s
              FOR JSON AUTO) sub(x)
OUTER APPLY (SELECT CONCAT('t', TransactiontypeId) AS Transactions, cnt 
            FROM (SELECT TransactiontypeId, COUNT(*) AS cnt
                  FROM tab t2 WHERE t2.UserId = t.UserId  
                  GROUP BY TransactiontypeId) s
              FOR JSON AUTO) sub2(x)
GROUP BY UserId;

<强> DBFiddle Demo

结果有点不同(键值数组)，但请将其视为起点。