JSON
JSON 数据类型，用二进制格式高效存储 JSON 数据，通过 JSON 函数访问其内部字段。
默认支持1048576 字节（1 MB），可调大到 2147483643 字节（2 GB），可通过 BE 配置string_type_length_soft_limit_bytes 调整。
与普通 String 类型存储的 JSON 字符串相比，JSON 类型有两点优势
1. 数据写入时进行 JSON 格式校验
2. 二进制存储格式更加高效，通过json_extract等函数可以高效访问JSON内部字段，比get_json_xx函数快几倍
:::caution[注意]
在1.2.x版本中，JSON 类型的名字是 JSONB，为了尽量跟 MySQL 兼容，从 2.0.0 版本开始改名为 JSON，老的表仍然可以使用。
:::
语法
定义
json_column_name JSON
写入
- INSERT INTO VALUE 格式是引号包围的字符串。例如：
INSERT INTO table_name(id, json_column_name) VALUES (1, '{"k1": "100"}')
- STREAM LOAD 对应列的格式是字符串，不需要额外引号包围。例如：
12 {"k1":"v31", "k2": 300}
13 []
14 [123, 456]
查询
- 直接将整个 JSON 列 SELECT 出来
SELECT json_column_name FROM table_name;
- 从 JSON 中提取需要的字段，或者其他信息，参考 JSON 函数，例如：
SELECT json_extract(json_column_name, '$.k1') FROM table_name;
- JSON 类型可以与整数、字符串、BOOLEAN、ARRAY、MAP 进行类型转换 CAST，例如：
SELECT CAST('{"k1": "100"}' AS JSON)
SELECT CAST(json_column_name AS String) FROM table_name;
SELECT CAST(json_extract(json_column_name, '$.k1') AS INT) FROM table_name;
提示
JSON 类型暂时不能用于 GROUP BY，ORDER BY，比较大小
使用示例
用一个从建表、导数据、查询全周期的例子说明JSON数据类型的功能和用法。
创建库表
CREATE DATABASE testdb;
USE testdb;
CREATE TABLE test_json (
id INT,
j JSON
)
DUPLICATE KEY(id)
DISTRIBUTED BY HASH(id) BUCKETS 10
PROPERTIES("replication_num" = "1");
导入数据
stream load 导入test_json.csv测试数据
- 测试数据有2列，第一列ID，第二列是JSON
- 测试数据有25行，其中前18行的JSON是合法的，后7行的JSON是非法的
1 \N
2 null
3 true
4 false
5 100
6 10000
7 1000000000
8 1152921504606846976
9 6.18
10 "abcd"
11 {}
12 {"k1":"v31", "k2": 300}
13 []
14 [123, 456]
15 ["abc", "def"]
16 [null, true, false, 100, 6.18, "abc"]
17 [{"k1":"v41", "k2": 400}, 1, "a", 3.14]
18 {"k1":"v31", "k2": 300, "a1": [{"k1":"v41", "k2": 400}, 1, "a", 3.14]}
19 ''
20 'abc'
21 abc
22 100x
23 6.a8
24 {x
25 [123, abc]
- 由于有28%的非法数据，默认会失败报错 "too many filtered rows"
curl --location-trusted -u root: -T test_json.csv http://127.0.0.1:8840/api/testdb/test_json/_stream_load
{
"TxnId": 12019,
"Label": "744d9821-9c9f-43dc-bf3b-7ab048f14e32",
"TwoPhaseCommit": "false",
"Status": "Fail",
"Message": "too many filtered rows",
"NumberTotalRows": 25,
"NumberLoadedRows": 18,
"NumberFilteredRows": 7,
"NumberUnselectedRows": 0,
"LoadBytes": 380,
"LoadTimeMs": 48,
"BeginTxnTimeMs": 0,
"StreamLoadPutTimeMs": 1,
"ReadDataTimeMs": 0,
"WriteDataTimeMs": 45,
"CommitAndPublishTimeMs": 0,
"ErrorURL": "http://172.21.0.5:8840/api/_load_error_log?file=__shard_2/error_log_insert_stmt_95435c4bf5f156df-426735082a9296af_95435c4bf5f156df_426735082a9296af"
}
- 设置容错率参数 'max_filter_ratio: 0.3'
curl --location-trusted -u root: -H 'max_filter_ratio: 0.3' -T test_json.csv http://127.0.0.1:8840/api/testdb/test_json/_stream_load
{
"TxnId": 12017,
"Label": "f37a50c1-43e9-4f4e-a159-a3db6abe2579",
"TwoPhaseCommit": "false",
"Status": "Success",
"Message": "OK",
"NumberTotalRows": 25,
"NumberLoadedRows": 18,
"NumberFilteredRows": 7,
"NumberUnselectedRows": 0,
"LoadBytes": 380,
"LoadTimeMs": 68,
"BeginTxnTimeMs": 0,
"StreamLoadPutTimeMs": 2,
"ReadDataTimeMs": 0,
"WriteDataTimeMs": 45,
"CommitAndPublishTimeMs": 19,
"ErrorURL": "http://172.21.0.5:8840/api/_load_error_log?file=__shard_0/error_log_insert_stmt_a1463f98a7b15caf-c79399b920f5bfa3_a1463f98a7b15caf_c79399b920f5bfa3"
}
- 查看stream load导入的数据，JSON类型的列j会自动转成JSON String展示
mysql> SELECT * FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+
| id | j |
+------+---------------------------------------------------------------+
| 1 | NULL |
| 2 | null |
| 3 | true |
| 4 | false |
| 5 | 100 |
| 6 | 10000 |
| 7 | 1000000000 |
| 8 | 1152921504606846976 |
| 9 | 6.18 |
| 10 | "abcd" |
| 11 | {} |
| 12 | {"k1":"v31","k2":300} |
| 13 | [] |
| 14 | [123,456] |
| 15 | ["abc","def"] |
| 16 | [null,true,false,100,6.18,"abc"] |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} |
+------+---------------------------------------------------------------+
18 rows in set (0.03 sec)
insert into 插入数据
- insert 1条数据，总数据从18条增加到19条
mysql> INSERT INTO test_json VALUES(26, '{"k1":"v1", "k2": 200}');
Query OK, 1 row affected (0.09 sec)
{'label':'insert_4ece6769d1b42fd_ac9f25b3b8f3dc02', 'status':'VISIBLE', 'txnId':'12016'}
mysql> SELECT * FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+
| id | j |
+------+---------------------------------------------------------------+
| 1 | NULL |
| 2 | null |
| 3 | true |
| 4 | false |
| 5 | 100 |
| 6 | 10000 |
| 7 | 1000000000 |
| 8 | 1152921504606846976 |
| 9 | 6.18 |
| 10 | "abcd" |
| 11 | {} |
| 12 | {"k1":"v31","k2":300} |
| 13 | [] |
| 14 | [123,456] |
| 15 | ["abc","def"] |
| 16 | [null,true,false,100,6.18,"abc"] |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} |
| 26 | {"k1":"v1","k2":200} |
+------+---------------------------------------------------------------+
19 rows in set (0.03 sec)
查询
用json_extract取json内的某个字段
- 获取整个json，$ 在json path中代表root，即整个json
+------+---------------------------------------------------------------+---------------------------------------------------------------+
| id | j | json_extract(`j`, '$') |
+------+---------------------------------------------------------------+---------------------------------------------------------------+
| 1 | NULL | NULL |
| 2 | null | null |
| 3 | true | true |
| 4 | false | false |
| 5 | 100 | 100 |
| 6 | 10000 | 10000 |
| 7 | 1000000000 | 1000000000 |
| 8 | 1152921504606846976 | 1152921504606846976 |
| 9 | 6.18 | 6.18 |
| 10 | "abcd" | "abcd" |
| 11 | {} | {} |
| 12 | {"k1":"v31","k2":300} | {"k1":"v31","k2":300} |
| 13 | [] | [] |
| 14 | [123,456] | [123,456] |
| 15 | ["abc","def"] | ["abc","def"] |
| 16 | [null,true,false,100,6.18,"abc"] | [null,true,false,100,6.18,"abc"] |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | [{"k1":"v41","k2":400},1,"a",3.14] |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} |
| 26 | {"k1":"v1","k2":200} | {"k1":"v1","k2":200} |
+------+---------------------------------------------------------------+---------------------------------------------------------------+
19 rows in set (0.03 sec)
- 获取k1字段，没有k1字段的行返回NULL
mysql> SELECT id, j, json_extract(j, '$.k1') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+----------------------------+
| id | j | json_extract(`j`, '$.k1') |
+------+---------------------------------------------------------------+----------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | "v31" |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | "v31" |
| 26 | {"k1":"v1","k2":200} | "v1" |
+------+---------------------------------------------------------------+----------------------------+
19 rows in set (0.03 sec)
- 获取顶层数组的第0个元素
mysql> SELECT id, j, json_extract(j, '$[0]') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+----------------------------+
| id | j | json_extract(`j`, '$[0]') |
+------+---------------------------------------------------------------+----------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | 123 |
| 15 | ["abc","def"] | "abc" |
| 16 | [null,true,false,100,6.18,"abc"] | null |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | {"k1":"v41","k2":400} |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | NULL |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+----------------------------+
19 rows in set (0.03 sec)
- 获取整个json array
mysql> SELECT id, j, json_extract(j, '$.a1') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+------------------------------------+
| id | j | json_extract(`j`, '$.a1') |
+------+---------------------------------------------------------------+------------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | [{"k1":"v41","k2":400},1,"a",3.14] |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+------------------------------------+
19 rows in set (0.02 sec)
- 获取json array中嵌套object的字段
mysql> SELECT id, j, json_extract(j, '$.a1[0]'), json_extract(j, '$.a1[0].k1') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+-------------------------------+----------------------------------+
| id | j | json_extract(`j`, '$.a1[0]') | json_extract(`j`, '$.a1[0].k1') |
+------+---------------------------------------------------------------+-------------------------------+----------------------------------+
| 1 | NULL | NULL | NULL |
| 2 | null | NULL | NULL |
| 3 | true | NULL | NULL |
| 4 | false | NULL | NULL |
| 5 | 100 | NULL | NULL |
| 6 | 10000 | NULL | NULL |
| 7 | 1000000000 | NULL | NULL |
| 8 | 1152921504606846976 | NULL | NULL |
| 9 | 6.18 | NULL | NULL |
| 10 | "abcd" | NULL | NULL |
| 11 | {} | NULL | NULL |
| 12 | {"k1":"v31","k2":300} | NULL | NULL |
| 13 | [] | NULL | NULL |
| 14 | [123,456] | NULL | NULL |
| 15 | ["abc","def"] | NULL | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | {"k1":"v41","k2":400} | "v41" |
| 26 | {"k1":"v1","k2":200} | NULL | NULL |
+------+---------------------------------------------------------------+-------------------------------+----------------------------------+
19 rows in set (0.02 sec)
- 获取具体类型的
- json_extract_string 获取String类型字段，非String类型转成String
mysql> SELECT id, j, json_extract_string(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+---------------------------------------------------------------+
| id | j | json_extract_string(`j`, '$') |
+------+---------------------------------------------------------------+---------------------------------------------------------------+
| 1 | NULL | NULL |
| 2 | null | null |
| 3 | true | true |
| 4 | false | false |
| 5 | 100 | 100 |
| 6 | 10000 | 10000 |
| 7 | 1000000000 | 1000000000 |
| 8 | 1152921504606846976 | 1152921504606846976 |
| 9 | 6.18 | 6.18 |
| 10 | "abcd" | abcd |
| 11 | {} | {} |
| 12 | {"k1":"v31","k2":300} | {"k1":"v31","k2":300} |
| 13 | [] | [] |
| 14 | [123,456] | [123,456] |
| 15 | ["abc","def"] | ["abc","def"] |
| 16 | [null,true,false,100,6.18,"abc"] | [null,true,false,100,6.18,"abc"] |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | [{"k1":"v41","k2":400},1,"a",3.14] |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} |
| 26 | {"k1":"v1","k2":200} | {"k1":"v1","k2":200} |
+------+---------------------------------------------------------------+---------------------------------------------------------------+
19 rows in set (0.02 sec)
mysql> SELECT id, j, json_extract_string(j, '$.k1') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+-----------------------------------+
| id | j | json_extract_string(`j`, '$.k1') |
+------+---------------------------------------------------------------+-----------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | v31 |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | v31 |
| 26 | {"k1":"v1","k2":200} | v1 |
+------+---------------------------------------------------------------+-----------------------------------+
19 rows in set (0.03 sec)
- json_extract_int 获取int类型字段，非int类型返回NULL
mysql> SELECT id, j, json_extract_int(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+-----------------------------+
| id | j | json_extract_int(`j`, '$') |
+------+---------------------------------------------------------------+-----------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | 100 |
| 6 | 10000 | 10000 |
| 7 | 1000000000 | 1000000000 |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | NULL |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+-----------------------------+
19 rows in set (0.02 sec)
mysql> SELECT id, j, json_extract_int(j, '$.k2') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+--------------------------------+
| id | j | json_extract_int(`j`, '$.k2') |
+------+---------------------------------------------------------------+--------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | 300 |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 300 |
| 26 | {"k1":"v1","k2":200} | 200 |
+------+---------------------------------------------------------------+--------------------------------+
19 rows in set (0.03 sec)
- json_extract_bigint 获取bigint类型字段，非bigint类型返回NULL
mysql> SELECT id, j, json_extract_bigint(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+--------------------------------+
| id | j | json_extract_bigint(`j`, '$') |
+------+---------------------------------------------------------------+--------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | 100 |
| 6 | 10000 | 10000 |
| 7 | 1000000000 | 1000000000 |
| 8 | 1152921504606846976 | 1152921504606846976 |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | NULL |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+--------------------------------+
19 rows in set (0.03 sec)
mysql> SELECT id, j, json_extract_bigint(j, '$.k2') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+-----------------------------------+
| id | j | json_extract_bigint(`j`, '$.k2') |
+------+---------------------------------------------------------------+-----------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | 300 |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 300 |
| 26 | {"k1":"v1","k2":200} | 200 |
+------+---------------------------------------------------------------+-----------------------------------+
19 rows in set (0.02 sec)
- json_extract_double 获取double类型字段，非double类型返回NULL
mysql> SELECT id, j, json_extract_double(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+--------------------------------+
| id | j | json_extract_double(`j`, '$') |
+------+---------------------------------------------------------------+--------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | 100 |
| 6 | 10000 | 10000 |
| 7 | 1000000000 | 1000000000 |
| 8 | 1152921504606846976 | 1.152921504606847e+18 |
| 9 | 6.18 | 6.18 |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | NULL |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+--------------------------------+
19 rows in set (0.02 sec)
mysql> SELECT id, j, json_extract_double(j, '$.k2') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+-----------------------------------+
| id | j | json_extract_double(`j`, '$.k2') |
+------+---------------------------------------------------------------+-----------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | 300 |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 300 |
| 26 | {"k1":"v1","k2":200} | 200 |
+------+---------------------------------------------------------------+-----------------------------------+
19 rows in set (0.03 sec)
- json_extract_bool 获取bool类型字段，非bool类型返回NULL
mysql> SELECT id, j, json_extract_bool(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+------------------------------+
| id | j | json_extract_bool(`j`, '$') |
+------+---------------------------------------------------------------+------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | 1 |
| 4 | false | 0 |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | NULL |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+------------------------------+
19 rows in set (0.01 sec)
mysql> SELECT id, j, json_extract_bool(j, '$[1]') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+---------------------------------+
| id | j | json_extract_bool(`j`, '$[1]') |
+------+---------------------------------------------------------------+---------------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | NULL |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | 1 |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | NULL |
| 26 | {"k1":"v1","k2":200} | NULL |
+------+---------------------------------------------------------------+---------------------------------+
19 rows in set (0.01 sec)
- json_extract_isnull 获取JSON NULL类型字段，null返回1，非null返回0
- 需要注意的是JSON NULL和SQL NULL不一样，SQL NULL表示某个字段的值不存在，而JSON表示值存在但是是一个特殊值NULL
mysql> SELECT id, j, json_extract_isnull(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+--------------------------------+
| id | j | json_extract_isnull(`j`, '$') |
+------+---------------------------------------------------------------+--------------------------------+
| 1 | NULL | NULL |
| 2 | null | 1 |
| 3 | true | 0 |
| 4 | false | 0 |
| 5 | 100 | 0 |
| 6 | 10000 | 0 |
| 7 | 1000000000 | 0 |
| 8 | 1152921504606846976 | 0 |
| 9 | 6.18 | 0 |
| 10 | "abcd" | 0 |
| 11 | {} | 0 |
| 12 | {"k1":"v31","k2":300} | 0 |
| 13 | [] | 0 |
| 14 | [123,456] | 0 |
| 15 | ["abc","def"] | 0 |
| 16 | [null,true,false,100,6.18,"abc"] | 0 |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | 0 |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 0 |
| 26 | {"k1":"v1","k2":200} | 0 |
+------+---------------------------------------------------------------+--------------------------------+
19 rows in set (0.03 sec)
用json_exists_path检查json内的某个字段是否存在
mysql> SELECT id, j, json_exists_path(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+-----------------------------+
| id | j | json_exists_path(`j`, '$') |
+------+---------------------------------------------------------------+-----------------------------+
| 1 | NULL | NULL |
| 2 | null | 1 |
| 3 | true | 1 |
| 4 | false | 1 |
| 5 | 100 | 1 |
| 6 | 10000 | 1 |
| 7 | 1000000000 | 1 |
| 8 | 1152921504606846976 | 1 |
| 9 | 6.18 | 1 |
| 10 | "abcd" | 1 |
| 11 | {} | 1 |
| 12 | {"k1":"v31","k2":300} | 1 |
| 13 | [] | 1 |
| 14 | [123,456] | 1 |
| 15 | ["abc","def"] | 1 |
| 16 | [null,true,false,100,6.18,"abc"] | 1 |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | 1 |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 1 |
| 26 | {"k1":"v1","k2":200} | 1 |
+------+---------------------------------------------------------------+-----------------------------+
19 rows in set (0.02 sec)
mysql> SELECT id, j, json_exists_path(j, '$.k1') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+--------------------------------+
| id | j | json_exists_path(`j`, '$.k1') |
+------+---------------------------------------------------------------+--------------------------------+
| 1 | NULL | NULL |
| 2 | null | 0 |
| 3 | true | 0 |
| 4 | false | 0 |
| 5 | 100 | 0 |
| 6 | 10000 | 0 |
| 7 | 1000000000 | 0 |
| 8 | 1152921504606846976 | 0 |
| 9 | 6.18 | 0 |
| 10 | "abcd" | 0 |
| 11 | {} | 0 |
| 12 | {"k1":"v31","k2":300} | 1 |
| 13 | [] | 0 |
| 14 | [123,456] | 0 |
| 15 | ["abc","def"] | 0 |
| 16 | [null,true,false,100,6.18,"abc"] | 0 |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | 0 |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 1 |
| 26 | {"k1":"v1","k2":200} | 1 |
+------+---------------------------------------------------------------+--------------------------------+
19 rows in set (0.03 sec)
mysql> SELECT id, j, json_exists_path(j, '$[2]') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+--------------------------------+
| id | j | json_exists_path(`j`, '$[2]') |
+------+---------------------------------------------------------------+--------------------------------+
| 1 | NULL | NULL |
| 2 | null | 0 |
| 3 | true | 0 |
| 4 | false | 0 |
| 5 | 100 | 0 |
| 6 | 10000 | 0 |
| 7 | 1000000000 | 0 |
| 8 | 1152921504606846976 | 0 |
| 9 | 6.18 | 0 |
| 10 | "abcd" | 0 |
| 11 | {} | 0 |
| 12 | {"k1":"v31","k2":300} | 0 |
| 13 | [] | 0 |
| 14 | [123,456] | 0 |
| 15 | ["abc","def"] | 0 |
| 16 | [null,true,false,100,6.18,"abc"] | 1 |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | 1 |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | 0 |
| 26 | {"k1":"v1","k2":200} | 0 |
+------+---------------------------------------------------------------+--------------------------------+
19 rows in set (0.02 sec)
用json_type获取JSON内的某个字段的类型
- 返回json path对应的JSON字段类型，如果不存在返回NULL
mysql> SELECT id, j, json_type(j, '$') FROM test_json ORDER BY id;
+------+---------------------------------------------------------------+----------------------+
| id | j | json_type(`j`, '$') |
+------+---------------------------------------------------------------+----------------------+
| 1 | NULL | NULL |
| 2 | null | null |
| 3 | true | bool |
| 4 | false | bool |
| 5 | 100 | int |
| 6 | 10000 | int |
| 7 | 1000000000 | int |
| 8 | 1152921504606846976 | bigint |
| 9 | 6.18 | double |
| 10 | "abcd" | string |
| 11 | {} | object |
| 12 | {"k1":"v31","k2":300} | object |
| 13 | [] | array |
| 14 | [123,456] | array |
| 15 | ["abc","def"] | array |
| 16 | [null,true,false,100,6.18,"abc"] | array |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | array |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | object |
| 26 | {"k1":"v1","k2":200} | object |
+------+---------------------------------------------------------------+----------------------+
19 rows in set (0.02 sec)
mysql> select id, j, json_type(j, '$.k1') from test_json order by id;
+------+---------------------------------------------------------------+-------------------------+
| id | j | json_type(`j`, '$.k1') |
+------+---------------------------------------------------------------+-------------------------+
| 1 | NULL | NULL |
| 2 | null | NULL |
| 3 | true | NULL |
| 4 | false | NULL |
| 5 | 100 | NULL |
| 6 | 10000 | NULL |
| 7 | 1000000000 | NULL |
| 8 | 1152921504606846976 | NULL |
| 9 | 6.18 | NULL |
| 10 | "abcd" | NULL |
| 11 | {} | NULL |
| 12 | {"k1":"v31","k2":300} | string |
| 13 | [] | NULL |
| 14 | [123,456] | NULL |
| 15 | ["abc","def"] | NULL |
| 16 | [null,true,false,100,6.18,"abc"] | NULL |
| 17 | [{"k1":"v41","k2":400},1,"a",3.14] | NULL |
| 18 | {"k1":"v31","k2":300,"a1":[{"k1":"v41","k2":400},1,"a",3.14]} | string |
| 26 | {"k1":"v1","k2":200} | string |
+------+---------------------------------------------------------------+-------------------------+
19 rows in set (0.03 sec)
keywords
JSON, json_parse, json_parse_error_to_null, json_parse_error_to_value, json_extract, json_extract_isnull, json_extract_bool, json_extract_int, json_extract_bigint, json_extract_double, json_extract_String, json_exists_path, json_type
