mariadb - MariaDB JSON_ARRAYAGG 给出错误的结果
问题描述
MariaDB 15.1 使用时有 2 个问题JSON_ARRAYAGG
括号[]
被省略
不正确的错误结果,值重复或省略
我的数据库如下:
用户:
+----+------+
| id | name |
+----+------+
| 1 | Jhon |
| 2 | Bob |
+----+------+
车:
+----+---------+-------------+
| id | user_id | model |
+----+---------+-------------+
| 1 | 1 | Tesla |
| 2 | 1 | Ferrari |
| 3 | 2 | Lamborghini |
+----+---------+-------------+
电话:
+----+---------+----------+--------+
| id | user_id | company | number |
+----+---------+----------+--------+
| 1 | 1 | Verzion | 1 |
| 2 | 1 | AT&T | 2 |
| 3 | 1 | T-Mobile | 3 |
| 4 | 2 | Sprint | 4 |
| 5 | 1 | Sprint | 2 |
+----+---------+----------+--------+
[]
1.省略括号
例如,这个查询获取用户的汽车列表:
SELECT
user.id AS id,
user.name AS name,
JSON_ARRAYAGG(
JSON_OBJECT(
'id', car.id,
'model', car.model
)
) AS cars
FROM user
INNER JOIN car ON user.id = car.user_id
GROUP BY user.id;
结果:括号[]
被省略cars
(JSON_ARRAYAGG
具有类似的行为GROUP_CONCAT
)
+----+------+-----------------------------------------------------------+
| id | name | cars |
+----+------+-----------------------------------------------------------+
| 1 | Jhon | {"id": 1, "model": "Tesla"},{"id": 2, "model": "Ferrari"} |
| 2 | Bob | {"id": 3, "model": "Lamborghini"} |
+----+------+-----------------------------------------------------------+
但是,在添加过滤器时,不会省略WHERE user.id = 1
括号:[]
+----+------+-------------------------------------------------------------+
| id | name | cars |
+----+------+-------------------------------------------------------------+
| 1 | Jhon | [{"id": 1, "model": "Tesla"},{"id": 2, "model": "Ferrari"}] |
+----+------+-------------------------------------------------------------+
2.不正确的错误结果,值重复或省略
这个错误很奇怪,因为必须满足以下条件:
- 咨询超过2张桌子
DISTINCT
必须使用该选项- 一个用户至少有 2 辆汽车和至少 3 部手机。
重复值
例如,这个查询获取用户的汽车列表和电话列表:
SELECT
user.id AS id,
user.name AS name,
JSON_ARRAYAGG( DISTINCT
JSON_OBJECT(
'id', car.id,
'model', car.model
)
) AS cars,
JSON_ARRAYAGG( DISTINCT
JSON_OBJECT(
'id', phone.id,
'company', phone.company,
'number', phone.number
)
) AS phones
FROM user
INNER JOIN car ON user.id = car.user_id
INNER JOIN phone ON user.id = phone.user_id
GROUP BY user.id;
我将以 json 格式保留输出,并且只保留感兴趣的元素。
结果:括号[]
被省略且重复Verizon
{
"id": 1,
"name": "Jhon",
"phones": // [ Opening bracket expected
{
"id": 5,
"company": "Sprint",
"number": 2
},
{
"id": 1,
"company": "Verzion",
"number": 1
},
{
"id": 1,
"company": "Verzion",
"number": 1
}, // Duplicate object with the DISTINCT option
{
"id": 2,
"company": "AT&T",
"number": 2
},
{
"id": 3,
"company": "T-Mobile",
"number": 3
}
// ] Closing bracket expected
}
省略的值
phone.id
查询中省略省略时出现此错误
SELECT
user.id AS id,
user.name AS name,
JSON_ARRAYAGG( DISTINCT
JSON_OBJECT(
'id', car.id,
'model', car.model
)
) AS cars,
JSON_ARRAYAGG( DISTINCT
JSON_OBJECT(
--'id', phone.id,
'company', phone.company,
'number', phone.number
)
) AS phones
FROM user
INNER JOIN car ON user.id = car.user_id
INNER JOIN phone ON user.id = phone.user_id
GROUP BY user.id;
结果:括号[]
被省略,Sprint
被省略。
显然,发生这种情况是因为它在 的列之间产生了 OR 类型JSON_OBJECT
,因为company
存在于不同的行和number
其他不同的行中
{
"id": 1,
"name": "Jhon",
"phones": // [ Opening bracket expected
//{
// "company": "Sprint",
// "number": 2
//}, `Sprint` was omitted
{
"company": "Verzion",
"number": 1
},
{
"company": "AT&T",
"number": 2
},
{
"company": "T-Mobile",
"number": 3
}
// ] Closing bracket expected
}
GROUP_CONCAT
实例JSON_ARRAYAGG
解决duplicate
或omitted
对象的问题
但是,通过添加 filter WHERE user.id = 1
,括号[]
没有省略,也解决了duplicate
oromitted
对象的问题:
{
"id": 1,
"name": "Jhon",
"phones": [
{
"id": 1,
"company": "Verzion",
"number": 1
},
{
"id": 2,
"company": "AT&T",
"number": 2
},
{
"id": 3,
"company": "T-Mobile",
"number": 3
},
{
"id": 5,
"company": "Sprint",
"number": 2
}
]
}
我究竟做错了什么?
解决方案
到目前为止,我的解决方案是这样,但我想使用 JSON_ARRAYAGG 因为查询更清晰
-- 1
SELECT
user.id AS id,
user.name AS name,
CONCAT(
'[',
GROUP_CONCAT( DISTINCT
JSON_OBJECT(
'id', car.id,
'model', car.model
)
),
']'
) AS cars
FROM user
INNER JOIN car ON user.id = car.user_id
GROUP BY user.id;
-- 2
SELECT
user.id AS id,
user.name AS name,
CONCAT(
'[',
GROUP_CONCAT( DISTINCT
JSON_OBJECT(
'id', car.id,
'model', car.model
)
),
']'
) AS cars,
CONCAT(
'[',
GROUP_CONCAT( DISTINCT
JSON_OBJECT(
'id', phone.id,
'company', phone.company,
'number', phone.number
)
),
']'
) AS phones
FROM user
INNER JOIN car ON user.id = car.user_id
INNER JOIN phone ON user.id = phone.user_id
GROUP BY user.id;