标签：Postgresql 递归 parent dictionaries children JSON lvl id name
现在有一张字典表，有二级 、三级字典项，需要递归查询并转换成JSON对象。字典数据情况如下：
查询语句如下：
WITH RECURSIVE c AS (
SELECT dictionaries_id,BIANMA,NAME,parent_id, 0 as lvl
FROM sys_dictionaries
WHERE dictionaries_id ='91f9e33300824f84a2a0b8780775fb2f' AND parent_id='0'
UNION ALL
SELECT d.dictionaries_id,d.BIANMA,d.NAME,d.parent_id, c.lvl + 1
FROM sys_dictionaries d
JOIN c ON d.parent_id = c.dictionaries_id
),
maxlvl AS (
SELECT max(lvl) maxlvl FROM c
),
j AS (
SELECT c.*, json '[]' children
FROM c, maxlvl
WHERE lvl = maxlvl
UNION ALL
SELECT (c).*, array_to_json(array_agg(j) || array(SELECT r
FROM (SELECT l.*, json '[]' children
FROM c l, maxlvl
WHERE l.parent_id = (c).dictionaries_id
AND l.lvl < maxlvl
AND NOT EXISTS (SELECT 1
FROM c lp
WHERE lp.parent_id = l.dictionaries_id)) r)) children
FROM (SELECT c, j
FROM c
JOIN j ON j.parent_id = c.dictionaries_id) v
GROUP BY v.c
)
SELECT row_to_json(j) json_tree
FROM j
WHERE lvl = 0;
查询结果类似这样:
{
"dictionaries_id": "91f9e33300824f84a2a0b8780775fb2f",
"bianma": "wp_sjyt",
"name": "合法图斑实际用途",
"parent_id": "0",
"lvl": 0,
"children": [
{
"dictionaries_id": "ca97634ca1ef4ae79d2397d398b75595",
"bianma": "01",
"name": "商服用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": [
{
"dictionaries_id": "b1e11a35b81b49e4a5d4d879d529d2f5",
"bianma": "01_07",
"name": "其他商服用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
},
{
"dictionaries_id": "87f5bf6d27e244a5b75c3c46a3ad1e11",
"bianma": "01_06",
"name": "娱乐用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
},
{
"dictionaries_id": "0ffbf2c61fee4886881ed9fbf4300a1b",
"bianma": "01_05",
"name": "商务金融用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
},
{
"dictionaries_id": "5f74e7d1710c49ef84360d6a7ef5ce2a",
"bianma": "01_04",
"name": "旅馆用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
},
{
"dictionaries_id": "0ad1d97089434c6b86b7b256bf572792",
"bianma": "01_03",
"name": "餐饮用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
},
{
"dictionaries_id": "e010e20ee128459aa23bceef95d7f6ae",
"bianma": "01_02",
"name": "批发市场用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
},
{
"dictionaries_id": "783da69c120c43d4bf23b9ea51ab5033",
"bianma": "01_01",
"name": "零售商业用地",
"parent_id": "ca97634ca1ef4ae79d2397d398b75595",
"lvl": 2,
"children": []
}
]
},
{
"dictionaries_id": "62fe418f9b084811b86f53f412fb87c1",
"bianma": "02",
"name": "工矿仓储用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
},
{
"dictionaries_id": "ea91d0e0035249d29755efbf9e386752",
"bianma": "03",
"name": "住宅用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
},
{
"dictionaries_id": "74c1c1571bd9419fa59aa8dd7820bec5",
"bianma": "04",
"name": "公共管理与公共服务用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
},
{
"dictionaries_id": "9369c75048aa489697a3242fd854802b",
"bianma": "05",
"name": "特殊用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
},
{
"dictionaries_id": "1e05348899754affa2663c31cf9815d3",
"bianma": "06",
"name": "交通运输用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
},
{
"dictionaries_id": "752406e52b9e473bb9f858268247a72e",
"bianma": "07",
"name": "水域及水利设施用地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
},
{
"dictionaries_id": "6ef459de851d48e1aae376150a74747e",
"bianma": "08",
"name": "其他土地",
"parent_id": "91f9e33300824f84a2a0b8780775fb2f",
"lvl": 1,
"children": []
}
]
}
标签：Postgresql,递归,parent,dictionaries,children,JSON,lvl,id,name 来源： https://www.cnblogs.com/codefree/p/16023064.html
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