概览
注：MySQL版本不同，所支持的方法也会有所差异。此文中部分方法需MySQL 8
创建JSON数据
搜索JSON数据内容
修改JSON数据
查看JSON数据属性
将JSON数据转换成关系型表
其它JSON方法
详述
JSON_ARRAY
创建一个JSON数组
JSON_ARRAY([val[, val] ...])
select JSON_ARRAY(1, "abc", NULL, TRUE, CURTIME());
+---------------------------------------------+ | JSON_ARRAY(1, "abc", NULL, TRUE, CURTIME()) | +---------------------------------------------+ | [1, "abc", null, true, "10:00:24.000000"] | +---------------------------------------------+
JSON_OBJECT
创建一个JSON对象
JSON_OBJECT([key, val[, key, val] ...])
select JSON_OBJECT('id', '1047', 'name', 'Author');
+---------------------------------------------+
| JSON_OBJECT('id', '1047', 'name', 'Author') |
+---------------------------------------------+
| {"id": "1047", "name": "Author"} |
+---------------------------------------------+
JSON_QUOTE
通过在一个字符串两端添加引号并对内部特殊字符进行转义得到一个JSON数据
JSON_QUOTE(string)
select JSON_QUOTE('null'), JSON_QUOTE('"null"');
+--------------------+----------------------+
| JSON_QUOTE('null') | JSON_QUOTE('"null"') |
+--------------------+----------------------+
| "null" | "\"null\"" |
+--------------------+----------------------+
转义字符表
JSON_UNQUOTE
JSON_QUOTE的反向操作
JSON_UNQUOTE(json_val)
select JSON_UNQUOTE('"abc"');
+-----------------------+
| JSON_UNQUOTE('"abc"') |
+-----------------------+
| abc |
+-----------------------+
JSON_CONTAINS
判断JSON数据中指定路径（path）的值是否与指定的值相等
JSON_CONTAINS(target, candidate[, path])
select JSON_CONTAINS('{"a":1}', '1', '$.a');
+--------------------------------------+
| JSON_CONTAINS('{"a":1}', '1', '$.a') |
+--------------------------------------+
| 1 |
+--------------------------------------+
select JSON_CONTAINS('{"a":1}', '0', '$.a');
+--------------------------------------+
| JSON_CONTAINS('{"a":1}', '0', '$.a') |
+--------------------------------------+
| 0 |
+--------------------------------------+
select JSON_CONTAINS('{"x":{"f1":"f"}}', '{"f1":"f"}', '$.x');
+--------------------------------------------------------+
| JSON_CONTAINS('{"x":{"f1":"f"}}', '{"f1":"f"}', '$.x') |
+--------------------------------------------------------+
| 1 |
+--------------------------------------------------------+
JSON_CONTAINS_PATH
判断JSON数据是否存在指定的路径（path）
JSON_CONTAINS_PATH(json_doc, one_or_all, path[, path] ...)
select JSON_CONTAINS_PATH('{"a":1}', 'one', '$.a', '$.b');
+----------------------------------------------------+
| JSON_CONTAINS_PATH('{"a":1}', 'one', '$.a', '$.b') |
+----------------------------------------------------+
| 1 |
+----------------------------------------------------+
select JSON_CONTAINS_PATH('{"a":1}', 'all', '$.a', '$.b');
+----------------------------------------------------+
| JSON_CONTAINS_PATH('{"a":1}', 'all', '$.a', '$.b') |
+----------------------------------------------------+
| 0 |
+----------------------------------------------------+
JSON_EXTRACT
获取JSON数据中指定路径（path）的内容
JSON_EXTRACT(json_doc, path[, path] ...)
select JSON_EXTRACT('[1,2]', '$[0]');
+-------------------------------+
| JSON_EXTRACT('[1,2]', '$[0]') |
+-------------------------------+
| 1 |
+-------------------------------+
->
简易版的JSON_EXTRACT
column->path
select f2, f2->'$.a' from t1;
+------------------+-----------+
| f2 | f2->'$.a' |
+------------------+-----------+
| {"a": 1, "b": 2} | 1 |
+------------------+-----------+
->>
column->>path
这三者等价：
- JSON_UNQUOTE(JSON_EXTRACT(column, path))
- JSON_UNQUOTE(column -> path)
- column -> path
JSON_KEYS
获取JSON数据中的key
JSON_KEYS(json_doc[, path])
select JSON_KEYS('{"a":1, "b":2}');
+-----------------------------+
| JSON_KEYS('{"a":1, "b":2}') |
+-----------------------------+
| ["a", "b"] |
+-----------------------------+
JSON_SEARCH
搜索JSON数据中指定JSON值的路径（path）
JSON_SEARCH(json_doc, one_or_all, search_str[, escape_char[, path] ...])
select JSON_SEARCH('["a", {"f":"a"}]', 'one', 'a');
+---------------------------------------------+
| JSON_SEARCH('["a", {"f":"a"}]', 'one', 'a') |
+---------------------------------------------+
| "$[0]" |
+---------------------------------------------+
select JSON_SEARCH('["a", {"f":"1ab2"}]', 'all', '%a%');
+---------------------------------------------+
| JSON_SEARCH('["a", {"f":"1ab2"}]', 'all', '%a%') |
+---------------------------------------------+
| ["$[0]", "$[1].f"] |
+---------------------------------------------+
JSON_ARRAY_APPEND
在JSON数组最后增加一项数据
JSON_ARRAY_APPEND(json_doc, path, val[, path, val] ...)
select JSON_ARRAY_APPEND('[1,[2]]', '$[1]', 3);
+-----------------------------------------+
| JSON_ARRAY_APPEND('[1,[2]]', '$[1]', 3) |
+-----------------------------------------+
| [1, [2, 3]] |
+-----------------------------------------+
JSON_ARRAY_INSERT
向JSON数组插入一项数据
JSON_ARRAY_INSERT(json_doc, path, val[, path, val] ...)
select JSON_ARRAY_INSERT('[1,[2]]', '$[1]', 3);
+-----------------------------------------+
| JSON_ARRAY_INSERT('[1,[2]]', '$[1]', 3) |
+-----------------------------------------+
| [1, 3, [2]] |
+-----------------------------------------+
JSON_INSERT
向JSON文档插入一项数据
JSON_INSERT(json_doc, path, val[, path, val] ...)
select JSON_INSERT('{}', '$.a', 3);
+-----------------------------+
| JSON_INSERT('{}', '$.a', 3) |
+-----------------------------+
| {"a": 3} |
+-----------------------------+
JSON_MERGE
合并JSON文档。MySQL 5.7.22 中，该方法已被废弃
JSON_MERGE(json_doc, json_doc[, json_doc] ...)
JSON_MERGE_PATCH
合并JSON文档。如果key已存在，将替换原值
JSON_MERGE_PATCH(json_doc, json_doc[, json_doc] ...)
JSON_MERGE_PRESERVE
合并JSON文档。如果key已存在，会合并原值和新值
JSON_MERGE_PRESERVE(json_doc, json_doc[, json_doc] ...)
set @x = '{"a": 1, "b": 2}',
@y = '{"a": 3, "c": 4}',
@z = '{"a": 5, "d": 6}';
select JSON_MERGE_PATCH(@x, @y, @z) AS Patch,
JSON_MERGE_PRESERVE(@x, @y, @x) AS Preserve;
+-------------------------------+------------------------------------------+
| Patch | Preserve |
+-------------------------------+------------------------------------------+
| {"a":5, "b":2, "c":4, "d": 6} | {"a": [1, 3, 5], "b": 2, "c": 4, "d": 6} |
+-------------------------------+------------------------------------------+
JSON_REMOVE
移除JSON文档中的数据
JSON_REMOVE(json_doc, path[, path] ...)
select JSON_REMOVE('[1, 2, 3]', '$[1]');
+----------------------------------+
| JSON_REMOVE('[1, 2, 3]', '$[1]') |
+----------------------------------+
| [1, 3] |
+----------------------------------+
JSON_REPLACE
替换JSON文档中的数据
JSON_REPLACE(json_doc, path, val[, path, val] ...)
select JSON_REPLACE('[1, 2, 3]', '$[1]', 'two');
+------------------------------------------+
| JSON_REPLACE('[1, 2, 3]', '$[1]', 'two') |
+------------------------------------------+
| [1, "two", 3] |
+------------------------------------------+
JSON_SET
更新JSON文档中的数据；如果key不存在，则插入新数据
JSON_SET(json_doc, path, val[, path, val] ...)
select JSON_SET('{"a":1}', '$.a', 'one', '$.b', 2);
+---------------------------------------------+
| JSON_SET('{"a":1}', '$.a', 'one', '$.b', 2) |
+---------------------------------------------+
| {"a": "one", "b": 2} |
+---------------------------------------------+
JSON_DEPTH
获取JSON文档的最大深度
JSON_DEPTH(json_doc)
select f2, JSON_DEPTH(f2) from t1;
+----------+----------------+ | f2 | JSON_DEPTH(f2) | +----------+----------------+ | NULL | NULL | | [] | 1 | | [1] | 2 | | [1, []] | 2 | | [1, [2]] | 3 | +----------+----------------+
JSON_LENGTH
获取JSON文档的（一级）数据项数量
JSON_LENGTH(json_doc[, pathj])
select f2, JSON_LENGTH(f2) from t1;
+-------------+-----------------+ | f2 | JSON_LENGTH(f2) | +-------------+-----------------+ | NULL | NULL | | [] | 0 | | [1] | 1 | | [1, []] | 2 | | [1, [2]] | 2 | | [1, [2, 3]] | 2 | +-------------+-----------------+
JSON_TYPE
查看JSON值的类型
JSON_TYPE(json_val)
select f2, JSON_TYPE(f2) from t1;
+------------------------------+---------------+
| f2 | JSON_TYPE(f2) |
+------------------------------+---------------+
| NULL | NULL |
| "xyz" | STRING |
| 123 | INTEGER |
| 3.14 | DECIMAL |
| "2018-09-20 15:22:40.000000" | DATETIME |
| {"a": 1} | OBJECT |
| [1, "two"] | ARRAY |
+------------------------------+---------------+
JSON_VALID
检查一个JSON值是否有效
JSON_VALID(val)
select f1, JSON_VALID(f1) from t1;
+------+----------------+
| f1 | JSON_VALID(f1) |
+------+----------------+
| a | 0 |
| "a" | 1 |
| [] | 1 |
| {} | 1 |
| NULL | NULL |
+------+----------------+
JSON_TABLE
将JSON数据转换成一个关系型表
JSON_TABLE(expr, path, COLUMNS (column_list) [AS] alias)
SELECT *
FROM
JSON_TABLE(
'[{"x":2,"y":"8"},{"x":"3","y":"7"},{"x":"4","y":6}]',
"$[*]" COLUMNS(
xval VARCHAR(100) PATH "$.x",
yval VARCHAR(100) PATH "$.y"
)
) AS jt1;
+------+------+ | xval | yval | +------+------+ | 2 | 8 | | 3 | 7 | | 4 | 6 | +------+------+
JSON_PRETTY
将JSON文档输出成易于阅读的格式
JSON_PRETTY(json_val)
SELECT JSON_PRETTY('{"a":"10","b":"15","x":"25"}');
+---------------------------------------------+
| JSON_PRETTY('{"a":"10","b":"15","x":"25"}') |
+---------------------------------------------+
| {
"a": "10",
"b": "15",
"x": "25"
} |
+---------------------------------------------+
JSON_STORAGE_FREE
获取JSON字段在当前存储块中的剩余可用空间
JSON_STORAGE_FREE(json_val)
JSON_STORAGE_SIZE
获取JSON字段所占用的存储空间（包括未真正使用的空间）
JSON_STORAGE_SIZE(json_val)
JSON路径（path）语法：《JSON Path Syntax》
更多JSON方法：JSON_ARRAYAGG、JSON_OBJECTAGG、ST_AsGeoJSON、ST_GeomFromGeoJSON
