Question

我们可能有很多要求将json存储到数据库。有时我们需要将JSON键集转换为表-行。如何在Mysql表中提取完整的json？

即低于json和要求是将每个集合存储为表中的一行。

'{
"log": [
{
"datetime": "2017-10-25 07:19:55",
"Activity": "Activity 1"
},
{
"datetime": "2017-10-25 07:20:05",
"Activity": "Activity 2"
},
{
"datetime": "2017-10-25 07:20:31",
"Activity": "Activity 3"
},
{
"datetime": "2017-10-25 07:20:31",
"Activity": "Activity 4"
},
{
"datetime": "2017-10-25 07:21:03",
"Activity": "Activity 5"
},
{
"datetime": "2017-10-25 13:56:42",
"Activity": "Activity 6"
},
{
"datetime": "2017-10-25 13:56:53",
"Activity": "Activity 7"
},
{
"datetime": "2017-10-25 13:57:03",
"Activity": "Activity 8"
},
{
"datetime": "2017-10-25 13:57:04",
"Activity": "Activity 9"
}, 
{ "datetime": "2017-10-25 13:57:53",
"Activity": "Activity 10"
},
{
"datetime": "2017-10-25 13:57:59",
"Activity": "Activity 11"
},
{
"datetime": "2017-10-25 13:58:01",
"Activity": "Activity 12"
},
{
"datetime": "2017-10-25 13:58:01",
"Activity": "Activity 13"
}
]
} '

Answer 1

MySQL 8.0具有JSON_TABLE函数：

parent_clip = VideoFileClip("./parent_video.mp4")
clip_list = []
for part in time_parts:
    time_start = part[0]
    time_end = part[1]
    clip_list.append(
        parent_clip.subclip(time_start, time_end)
    )
concat_clip = concatenate_videoclips(clip_list)

Answer 2

JSON可以存储在具有不同数据类型的数据库中。即JSON，VACRHAR，TEXT ...等。对于导出报告或过滤JSON元素值，我们应该有不同的解决方案来完成它。

创建表以将JSON存储在MySQL表中。

CREATE TABLE test_Json(id INT, activity_log JSON);

将示例数据插入表中。 JSON字段数据已插入JSON数据类型，但也可以是VARCHAR或Text类型。

INSERT INTO test_Json(id, activity_log)
VALUES(1,
'{
"log": [
{
"datetime": "2017-10-25 07:19:55",
"Activity": "Activity 1"
},
{
"datetime": "2017-10-25 07:20:05",
"Activity": "Activity 2"
},
{
"datetime": "2017-10-25 07:20:31",
"Activity": "Activity 3"
},
{
"datetime": "2017-10-25 07:20:31",
"Activity": "Activity 4"
},
{
"datetime": "2017-10-25 07:21:03",
"Activity": "Activity 5"
},
{
"datetime": "2017-10-25 13:56:42",
"Activity": "Activity 6"
},
{
"datetime": "2017-10-25 13:56:53",
"Activity": "Activity 7"
},
{
"datetime": "2017-10-25 13:57:03",
"Activity": "Activity 8"
},
{
"datetime": "2017-10-25 13:57:04",
"Activity": "Activity 9"
}, { "datetime": "2017-10-25 13:57:53",
"Activity": "Activity 10"
},
{
"datetime": "2017-10-25 13:57:59",
"Activity": "Activity 11"
},
{
"datetime": "2017-10-25 13:58:01",
"Activity": "Activity 12"
},
{
"datetime": "2017-10-25 13:58:01",
"Activity": "Activity 13"
}
]
} ');

INSERT INTO test_Json(id, activity_log)
VALUES(2,'
{
"log": [
{ "datetime": "2017-10-29 21:56:27",
"Activity": "Activity-11"
},
{
"datetime": "2017-10-29 21:56:27",
"Activity": "Activity-12"
},
{
"datetime": "2017-10-29 21:56:27",
"Activity": "Activity-13"
},
{
"datetime": "2017-10-29 21:56:27",
"Activity": "Activity-14"
},
{
"datetime": "2017-10-29 21:56:35",
"Activity": "Activity-15"
},
{
"datetime": "2017-10-29 21:56:49",
"Activity": "Activity-16"
},
{
"datetime": "2017-10-29 21:56:49",
"Activity": "Activity-17"
},
{
"datetime": "2017-10-29 21:56:49",
"Activity": "Activity-18"
}
]
}');

查询以将JSON导出为具有JSON长度值的JSON数组

SELECT TJ.id,
JSON_LENGTH(JSON_EXTRACT(TJ.activity_log, '$**.datetime')) as Json_Length,
JSON_EXTRACT(TJ.activity_log, '$**.datetime') as json_array_message,
JSON_EXTRACT(TJ.activity_log, '$**.Activity') as json_array_datetime
FROM test_Json TJ
WHERE JSON_VALID(TJ.activity_log) = 1;

JSON_VALID()将验证JSON列数据，无论JSON数据是否正确。如果没有，那么它将被从查询中过滤掉。

递归CTE（公用表表达式）以行格式获取n级元素值

WITH RECURSIVE CTE_json (id, array_datetime, array_message,seq) AS
(
SELECT id, 
JSON_EXTRACT(JSON_EXTRACT(activity_log, '$**.datetime'), CONCAT('$[', 0, ']')), 
JSON_EXTRACT(JSON_EXTRACT(activity_log, '$**.Activity'), CONCAT('$[', 0, ']')), 
0 as seq
FROM test_Json
UNION ALL
SELECT TJ.id, 
JSON_EXTRACT(JSON_EXTRACT(TJ.activity_log, '$**.datetime'), CONCAT('$[', rc.seq +1, ']')) as array_datetime, 
JSON_EXTRACT(JSON_EXTRACT(TJ.activity_log, '$**.Activity'), CONCAT('$[', rc.seq +1, ']')) as array_message, 
rc.seq +1 AS seq
FROM CTE_json rc
INNER JOIN test_Json TJ ON rc.id = TJ.id
WHERE rc.seq+1 < JSON_LENGTH(JSON_EXTRACT(TJ.activity_log, '$**.datetime'))
)

SELECT *
FROM CTE_json cj
ORDER BY id, seq;

如果当前的MySQL版本不支持递归CTE，则我们可以使用其他LOOP替代方法。

JSON元素到行或JSON到表MYSQL中的行（在MySQL中导出JSON）

2 个答案: