我的 jQuery 代码需要这个 JSON:
{
"projects": [
{
"id": "1",
"project_name": "Carmichael House",
"parent_id": "0",
"children": [
{
"id": "2",
"project_name": "Carmichael Kitchen",
"parent_id": "1"
},
{
"id": "3",
"project_name": "Carmichael Bathroom",
"parent_id": "1"
}
]
},
{
"id": "2",
"project_name": "Dowd Apartment",
"parent_id": "0",
"children": [
{
"id": "4",
"project_name": "Dowd Kitchen",
"parent_id": "2"
}
]
}
]
}
此数据将来自 MySql 表 tbl_projects
:
id
project_name
parent_id
SQL SELECT
查询应该是什么,以便它输出 1 个平面表,可以轻松转换为 JSON(在 PHP 或 JavaScript/jQuery 中)?
我的处理方式是否正确?
最佳答案
您可以直接从 MySQL 生成 JSON 内容。这是适用于 MySQL 5.7 或更高版本的解决方案。
首先,考虑 function JSON_OBJECT()
,为表中的每条记录生成一个 JSON 对象:
SELECT
p.*,
JSON_OBJECT('id', id, 'project_name', project_name, 'parent_id', parent_id) js
FROM tbl_projects p;
根据您的样本数据,这将返回:
| id | project_name | parent_id | js |
| --- | ------------------- | --------- | ---------------------------------------------------------------- |
| 1 | Carmichael House | 0 | {"id": 1, "parent_id": 0, "project_name": "Carmichael House"} |
| 2 | Carmichael Kitchen | 1 | {"id": 2, "parent_id": 1, "project_name": "Carmichael Kitchen"} |
| 3 | Carmichael Bathroom | 1 | {"id": 3, "parent_id": 1, "project_name": "Carmichael Bathroom"} |
| 4 | Dowd Apartment | 0 | {"id": 4, "parent_id": 0, "project_name": "Dowd Apartment"} |
| 5 | Dowd Kitchen | 4 | {"id": 5, "parent_id": 4, "project_name": "Dowd Kitchen"} |
为了生成您预期的输出,我们将自行JOIN
表以查找子记录,并使用aggregate function JSON_ARRAYAGG()
。生成内部 JSON 数组。一个额外的聚合层次将所有东西都塞进一个单一的对象中。如您的示例数据所示,我假设根项目有 parent_id = 0
并且只有一层层次结构:
SELECT JSON_OBJECT('projects', JSON_ARRAYAGG(js)) results
FROM (
SELECT JSON_OBJECT(
'id', p.id,
'project_name', p.project_name,
'parent_id', p.parent_id,
'children', JSON_ARRAYAGG(
JSON_OBJECT(
'id', p1.id,
'project_name', p1.project_name,
'parent_id', p1.parent_id
)
)
) js
FROM tbl_projects p
LEFT JOIN tbl_projects p1 ON p.id = p1.parent_id
WHERE p.parent_id = 0
GROUP BY p.id, p.project_name, p.parent_id
) x
产量:
| results |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| {"projects": [{"id": 1, "children": [{"id": 2, "parent_id": 1, "project_name": "Carmichael Kitchen"}, {"id": 3, "parent_id": 1, "project_name": "Carmichael Bathroom"}], "parent_id": 0, "project_name": "Carmichael House"}, {"id": 4, "children": [{"id": 5, "parent_id": 4, "project_name": "Dowd Kitchen"}], "parent_id": 0, "project_name": "Dowd Apartment"}]} |
关于php - 如何 SQL 查询特定 JSON 格式的父子关系?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55211880/