金仓数据库KingbaseES Json 系列六--Json记录操作函数一

数据猿 2023-04-13

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KingbaseES Json 系列六–Json记录操作函数一

(JSONB_TO_RECORD,JSONB_TO_RECORDSET,JSON_TO_RECORD,JSON_TO_RECORDSET)

JSON 数据类型是用来存储 JSON(JavaScript Object Notation)数据的。KingbaseES为存储JSON数据提供了两种类型:JSON和 JSONB。JSON 和 JSONB 几乎接受完全相同的值集合作为输入。
本文将主要介绍Kingbase数据库的Json记录操作函数第一部分。

准备数据：

CREATE TABLE "public"."jsontable" (
	"id" integer NULL,
	"jsondata" json NULL,
	"jsonvarchar" varchar NULL,
	"jsonarray" json NULL,
	"jsonrecord" json NULL,
	"jsonset" json NULL
);

INSERT INTO "public"."jsontable" ("id","jsondata","jsonvarchar","jsonarray","jsonrecord","jsonset") VALUES
	 (1,'{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}','{"f2": {"f3": 1}, "f4": {"f5": 99, "f6": "foo"}}','[1,true,[1,[2,3]],null,{"f1":1,"f2":[7,8,9]},false,"stringy"]','{"a":1,"b":"bcol","c":"cc"}','[{"a":1,"b":"bcol","c":"cc"},{"a":1,"b":"bcol","d":""}]'),
	 (2,'{"a":[1,2,3,4,5]}','{"a": [1, 2, 3, 4, 5]}','[1,2,3,4,5]','{"a":1,"b":"bcol","c":""}','[{"a":1,"b":"bcol","c":""},{"a":1,"b":"bcol","e":""}]'),
	 (3,'{"a":1, "b": ["2", "a b"],"c": {"d":4, "e": "ab c"}}','{"a": 1, "b": ["2", "a b"], "c": {"d": 4, "e": "ab c"}}','[{"f1":1,"f2":null},2,null,3]','{"a":1,"b":"bcol","d":"dd"}','[{"a":1,"b":"bcol","c":"cc_3_1"},{"a":1,"b":"bcol","c":"cc_3_2"}]');

json函数简介

JSONB_TO_RECORD

功能：

JSON函数，从一个JSON对象构建一个任意的记录，正如所有返回 record 的函数一样，调用者必须用一个 AS 子句显式的定义记录的结构。

用法：

jsonb_to_record(jsonb)

示例：

-- 解析json数据

demo=# SELECT * FROM jsonb_to_record('{"a":1,"b":[1,2,3],"c":[1,2,3],"e":"bar","r": {"a": 123, "b": "a b c"}}') as x(a int,b text);                  
 a |     b     
---+-----------
 1 | [1, 2, 3]
(1 行记录)

-- 数据value的类型需要能够隐式转换到record的匹配类型中

demo=# SELECT * FROM jsonb_to_record('{"a":1,"b":[1,2,3],"c":[1,2,3],"e":"bar","r": {"a": 123, "b": "a b c"}}') as x(a int,b text, c boolean[]);
错误:  无效的类型 boolean 输入语法: "2"

demo=# SELECT * FROM jsonb_to_record('{"a":1,"b":[1,2,3],"c":[1,2,3],"e":"bar","r": {"a": 123, "b": "a b c"}}') as x(a int,b text, c int[]);    
 a |     b     |    c    
---+-----------+---------
 1 | [1, 2, 3] | {1,2,3}
(1 行记录)

-- 数据中不存在record定义的属性时，默认返回null

demo=# SELECT * FROM jsonb_to_record('{"a":1,"b":[1,2,3],"c":[1,2,3],"e":"bar","r": {"a": 123, "b": "a b c"}}') as x(a int,b text, c text[], d text);
 a |     b     |    c    | d 
---+-----------+---------+---
 1 | [1, 2, 3] | {1,2,3} | 
(1 行记录)

-- 从表字段中解析数据

demo=# select jt.jsonrecord , x.*  from  jsontable jt , jsonb_to_record(jt.jsonrecord) as x(a int , b text , c text) ;
         jsonrecord          | a |  b   | c  
-----------------------------+---+------+----
 {"a":1,"b":"bcol","c":"cc"} | 1 | bcol | cc
 {"a":1,"b":"bcol","c":""}   | 1 | bcol | 
 {"a":1,"b":"bcol","d":"dd"} | 1 | bcol | 
(3 行记录)

JSONB_TO_RECORDSET

功能：

JSON函数，从一个JSON对象数组构建一个任意的记录集合，正如所有返回 record 的函数一样，调用者必须用一个 AS 子句显式的定义记录的结构。

用法：

jsonb_to_recordset(jsonb)

示例：

-- 解析json数据

demo=# SELECT * FROM jsonb_to_recordset ('[{"a":1,"b":"foo","c":true},{"a":"2","b":"bar"}]')as x(a int, b text);
 a |  b  
---+-----
 1 | foo
 2 | bar
(2 行记录)

-- 数据value的类型需要能够隐式转换到record的匹配类型中

demo=# SELECT * FROM jsonb_to_recordset ('[{"a":1,"b":"foo","c":true},{"a":"2","b":"bar"}]')as x(a int, b text,c int);

错误:  无效的类型 integer 输入语法: "true"

demo=# SELECT * FROM jsonb_to_recordset ('[{"a":1,"b":"foo","c":true},{"a":"2","b":"bar"}]')as x(a int, b text,c boolean);
 a |  b  | c 
---+-----+---
 1 | foo | t
 2 | bar | 
(2 行记录)

-- 数据中不存在record定义的属性时，默认返回null

demo=# SELECT * FROM jsonb_to_recordset ('[{"a":1,"b":"foo","c":true},{"a":"2","b":"bar"}]')as x(a int, b text,c boolean,d int);
 a |  b  | c | d 
---+-----+---+---
 1 | foo | t |  
 2 | bar |   |  
(2 行记录)

-- 从表字段中解析数据

demo=# select jt.jsonset , x.*  from  jsontable jt , jsonb_to_recordset(jt.jsonset) as x(a int , b text , c text) ;
                              jsonset                              | a |  b   |   c    
-------------------------------------------------------------------+---+------+--------
 [{"a":1,"b":"bcol","c":"cc"},{"a":1,"b":"bcol","d":""}]           | 1 | bcol | cc
 [{"a":1,"b":"bcol","c":"cc"},{"a":1,"b":"bcol","d":""}]           | 1 | bcol | 
 [{"a":1,"b":"bcol","c":""},{"a":1,"b":"bcol","e":""}]             | 1 | bcol | 
 [{"a":1,"b":"bcol","c":""},{"a":1,"b":"bcol","e":""}]             | 1 | bcol | 
 [{"a":1,"b":"bcol","c":"cc_3_1"},{"a":1,"b":"bcol","c":"cc_3_2"}] | 1 | bcol | cc_3_1
 [{"a":1,"b":"bcol","c":"cc_3_1"},{"a":1,"b":"bcol","c":"cc_3_2"}] | 1 | bcol | cc_3_2
(6 行记录)

JSON_TO_RECORD

功能：