单表的内部连接的SQL计数

Question

我有一张这样的表：

ycsb=# select * from pgstatindex('usertable_pkey');
 version | tree_level | index_size | root_block_no | internal_pages | leaf_pages | empty_pages | deleted_pages | avg_leaf_density | leaf_fragmentation 
---------+------------+------------+---------------+----------------+------------+-------------+---------------+------------------+--------------------
       2 |          3 | 5488721920 |         44337 |           4464 |     665545 |           0 |             0 |               52 |                 11
(1 row)

我想选择每个名称，按ID分组并计算事务（NOT SUM）。所以我想要下表：

Name    Id      Amount 
Name1   1       99
Name1   1       30
Name1   9       120.2
Name2   21      348
Name2   21      21
Name3   41      99

我试过这个sql：

Name    Id      Count 
Name1   1       2
Name1   9       1
Name2   21      2
Name3   41      1

但是我收到以下错误：SELECT [Name], [Id] FROM table1 A INNER JOIN ( SELECT [Id], count([Amount]) as 'Count' FROM table1 GROUP BY [Id] ) B ON A.[Id] = B.[Id]

我做错了什么？

Answer 1

SELECT
       [Name],
       [Id],
       count([Amount]) as 'Count'
FROM 
       table1
GROUP BY [Name], [Id]

Answer 2

SELECT
A.[Name],
A.[Id]
FROM table1 A
INNER JOIN (
            SELECT
            table1.[Id],
            count([Amount]) as 'Count'
            FROM 
                table1
            GROUP BY table1.[Id]
       )
B ON A.[Id] = B.[Id]