[英]How to extract values from column of mysql table having partial Json array values and remaining with string values
[英]how to extract json array as table from mysql text column when number of json objects in array is unknown?
有没有一种方法可以从包含带有不同数量json对象的json数组的文本列中提取数据到表?
例如,如果我...
CREATE TABLE tableWithJsonStr (location TEXT, jsonStr TEXT);
INSERT INTO tableWithJsonStr VALUES
('Home', '[{"animalId":"1","type":"dog", "color":"white","isPet":"1"},{"animalId":"2","type":"cat", "color":"brown","isPet":"1"}]'),
('Farm', '[{"animalId":"8","type":"cow", "color":"brown","isPet":"0"}, {"animalId":"33","type":"pig", "color":"pink","isPet":"0"}, {"animalId":"22","type":"horse", "color":"black","isPet":"1"}]'),
('Zoo', '[{"animalId":"5","type":"tiger", "color":"stripes","isPet":"0"}]');
和
CREATE TABLE animal (
location TEXT,
idx INT,
animalId INT,
type TEXT,
color TEXT,
isPet BOOLEAN
);
我可以通过运行以下命令提取tableWithJsonStr.jsonStr:
INSERT INTO animal
SELECT location,
idx AS id,
TRIM(BOTH'"' FROM JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].animalId'))) AS animalId,
TRIM(BOTH'"' FROM JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].type'))) AS type,
TRIM(BOTH'"' FROM JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].color'))) AS color,
TRIM(BOTH'"' FROM JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].isPet'))) AS isPet
FROM tableWithJsonStr
JOIN(
SELECT 0 AS idx UNION
SELECT 1 AS idx UNION
SELECT 2 AS idx UNION
SELECT 3 AS idx
) AS indexes
WHERE JSON_EXTRACT(jsonStr, CONCAT('$[', idx, ']')) IS NOT NULL;
动物表的结果是:
| location | idx | animalId | type | color | isPet |
|==========|=====|==========|=======|=========|=======|
| Farm | 0 | 8 | cow | brown | 0 |
| Farm | 1 | 33 | pig | pink | 0 |
| Farm | 2 | 22 | horse | black | 1 |
| Home | 0 | 1 | dog | white | 1 |
| Home | 1 | 2 | cat | brown | 1 |
| Zoo | 0 | 5 | tiger | stripes | 0 |
尽管该解决方案有效,但它是不可扩展的。 如果我的json数组中有3个以上的对象,除非我在JOIN中添加另一个SELECT 4 AS idx,否则不会考虑它们。 有没有更好的方法可以遍历数组中不需要预先知道每个数组中可能存在的最大对象数的对象?
如果您使用的是MySQL 8.0,则可以使用JSON_TABLE
命令从JSON
每一行提取数据:
SELECT t1.location, farm.*
FROM tableWithJsonStr t1
JOIN JSON_TABLE(t1.jsonStr,
'$[*]'
COLUMNS (idx FOR ORDINALITY,
animalId INT PATH '$.animalId',
type TEXT PATH '$.type',
color TEXT PATH '$.color',
isPet BOOLEAN PATH '$.isPet')
) farm
ORDER BY location, idx
输出:
location idx animalId type color isPet
Farm 1 8 cow brown 0
Farm 2 33 pig pink 0
Farm 3 22 horse black 1
Home 1 1 dog white 1
Home 2 2 cat brown 1
Zoo 1 5 tiger stripes 0
如果您坚持使用MySQL 5.7,则可以使用存储过程来提取数据:
DELIMITER $$
CREATE PROCEDURE extract_animals()
BEGIN
DECLARE idx INT;
DECLARE finished INT DEFAULT 0;
DECLARE location, json VARCHAR(200);
DECLARE json_cursor CURSOR FOR SELECT location, jsonStr FROM tableWithJsonStr;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET finished = 1;
DROP TABLE IF EXISTS animal;
CREATE TABLE animal (location TEXT, idx INT, animalId INT, type TEXT, color TEXT, isPet BOOLEAN);
OPEN json_cursor;
json_loop: LOOP
FETCH json_cursor INTO location, json;
IF finished = 1 THEN
LEAVE json_loop;
END IF;
SET idx = 0
WHILE JSON_CONTAINS_PATH(json, 'one', CONCAT('$[', idx, ']))
INSERT INTO animal VALUES(location,
idx,
JSON_UNQUOTE(JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].animalId'))),
JSON_UNQUOTE(JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].type'))),
JSON_UNQUOTE(JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].color'))),
JSON_UNQUOTE(JSON_EXTRACT(jsonStr, CONCAT('$[', idx, '].isPet')));
SET idx = idx + 1;
END WHILE;
END LOOP json_loop;
END $$
输出:
location idx animalId type color isPet
Home 0 1 dog white 1
Home 1 2 cat brown 1
Farm 0 8 cow brown 0
Farm 1 33 pig pink 0
Farm 2 22 horse black 1
Zoo 0 5 tiger stripes 0
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