Question

我正在尝试group这样的结果，而不是像这样：

id  | nome  |  bairro
---------------------
1 . |Test 1 | bairro 1
1 . |Test 1 | bairro 2
2 . |Test 2 | bairro 3

它看起来像这样：

id  | nome  |  bairro
----------------------
1 . |Test 1 | bairro 1, bairro 2
2 . |Test 2 | bairro 3

“ id”和“ nome”在表1中，“ bairro”在“ nome”列的table 3中。

表1

id  | nome  | situacao
--------------------
1 . |Test 1 | EM_ATIVIDADE
2 . |Test 2 | EM_ATIVIDADE

表2

id  | escola (fgk table 1) | bairro (fgk table 3)
-------------------------------------------------
1 . | 2                    | 1
2 . | 2                    | 2

表3

id  | nome     
---------------
1 . | bairro 1 
2 . | bairro 2

我正在尝试使用LISTAGG和以下代码进行操作：

SELECT table1.nome, table1.id, LISTAGG(table3.nome, ', ') WITHIN GROUP (ORDER BY table3.nome) as "bairro"
FROM table1
LEFT JOIN table2 on table2.escola = table1.id
LEFT JOIN table3 on table3.id = table2.bairro
WHERE table1.situacao = 'EM_ATIVIDADE'
GROUP BY table1.id, table1.nome
ORDER BY table1.id

执行此操作时，出现错误

ORA-00979：不是按表达式分组

有人可以帮助我吗？我是初学者

edit ：已经尝试将table1.nome添加到我的分组依据。

Answer 1

我认为这是因为您正在使用一个聚合函数，该函数返回单行，而列将返回多行。因此，您需要对GROUP BY子句中的每个“常规”列进行分组，或者对“常规”列中的值（例如MIN，MAX，SUM等）应用一些汇总函数。

在您的示例中，它将类似于

pip install --upgrade scikit-image

或

SELECT table1.nome, table1.id, LISTAGG(table2.nome, ', ') WITHIN GROUP (ORDER BY table2.nome) as "bairro"
FROM table1
LEFT JOIN table2 on table2.escola = table1.id
LEFT JOIN table3 on table3.id = table2.bairro
WHERE table1.situacao = 'EM_ATIVIDADE'
GROUP BY table1.nome, table1.id
ORDER BY table1.id

还有一种替代方法，就是使用

SELECT MAX(table1.nome), MAX(table1.id), LISTAGG(table2.nome, ', ') WITHIN GROUP (ORDER BY table2.nome) as "bairro"
FROM table1
LEFT JOIN table2 on table2.escola = table1.id
LEFT JOIN table3 on table3.id = table2.bairro
WHERE table1.situacao = 'EM_ATIVIDADE'
ORDER BY table1.id

条款，例如像

OVER (partition BY <column name here>)

有关示例，请参见Oracle docs。

Answer 2

尝试将您的代码修改为以下内容；

SELECT table1.nome, table1.id, LISTAGG(table1.nome, ', ') WITHIN GROUP (ORDER BY table1.nome, table1.id) as "bairro"
FROM table1
LEFT JOIN table2 on table2.escola = table1.id
LEFT JOIN table3 on table3.id = table2.bairro
WHERE table1.situacao = 'EM_ATIVIDADE'
GROUP BY table1.id, table1.nome
ORDER BY table1.id, table1.nome

我在GROUP BY中添加了所有非LISTAGG选定的列，也将它们添加到了LISTAGG's ORDER BY子句中。

除此之外，我还向整个查询的table1.nome中添加了ORDER BY，因为我发现执行后显然会更好。

希望我能帮上忙！

为什么在尝试使用LISTAGG和LEFT JOIN时得到ORA-00979？

2 个答案: