12.17.3 Functions That Search JSON Values (original) (raw)

12.17.3 Functions That Search JSON Values

The functions in this section perform search operations on JSON values to extract data from them, report whether data exists at a location within them, or report the path to data within them.

JSON_CONTAINS(target,candidate[,path])
Indicates by returning 1 or 0 whether a given_candidate_ JSON document is contained within a target JSON document, or—if a path argument was supplied—whether the candidate is found at a specific path within the target. ReturnsNULL if any argument isNULL, or if the path argument does not identify a section of the target document. An error occurs if_target_ or_candidate_ is not a valid JSON document, or if the path argument is not a valid path expression or contains a* or ** wildcard.
To check only whether any data exists at the path, useJSON_CONTAINS_PATH() instead.
The following rules define containment:
- A candidate scalar is contained in a target scalar if and only if they are comparable and are equal. Two scalar values are comparable if they have the sameJSON_TYPE() types, with the exception that values of types INTEGER and DECIMAL are also comparable to each other.
- A candidate array is contained in a target array if and only if every element in the candidate is contained in some element of the target.
- A candidate nonarray is contained in a target array if and only if the candidate is contained in some element of the target.
- A candidate object is contained in a target object if and only if for each key in the candidate there is a key with the same name in the target and the value associated with the candidate key is contained in the value associated with the target key.
  Otherwise, the candidate value is not contained in the target document.

mysql> SET @j = '{"a": 1, "b": 2, "c": {"d": 4}}';  
mysql> SET @j2 = '1';  
mysql> SELECT JSON_CONTAINS(@j, @j2, '$.a');  
+-------------------------------+  
| JSON_CONTAINS(@j, @j2, '$.a') |  
+-------------------------------+  
|                             1 |  
+-------------------------------+  
mysql> SELECT JSON_CONTAINS(@j, @j2, '$.b');  
+-------------------------------+  
| JSON_CONTAINS(@j, @j2, '$.b') |  
+-------------------------------+  
|                             0 |  
+-------------------------------+  
mysql> SET @j2 = '{"d": 4}';  
mysql> SELECT JSON_CONTAINS(@j, @j2, '$.a');  
+-------------------------------+  
| JSON_CONTAINS(@j, @j2, '$.a') |  
+-------------------------------+  
|                             0 |  
+-------------------------------+  
mysql> SELECT JSON_CONTAINS(@j, @j2, '$.c');  
+-------------------------------+  
| JSON_CONTAINS(@j, @j2, '$.c') |  
+-------------------------------+  
|                             1 |  
+-------------------------------+

JSON_CONTAINS_PATH(json_doc,one_or_all,path[,path] ...)
Returns 0 or 1 to indicate whether a JSON document contains data at a given path or paths. Returns NULL if any argument is NULL. An error occurs if the jsondoc argument is not a valid JSON document, any path argument is not a valid path expression, or_oneorall_ is not'one' or 'all'.
To check for a specific value at a path, useJSON_CONTAINS() instead.
The return value is 0 if no specified path exists within the document. Otherwise, the return value depends on the_oneorall_ argument:
- 'one': 1 if at least one path exists within the document, 0 otherwise.
- 'all': 1 if all paths exist within the document, 0 otherwise.

mysql> SET @j = '{"a": 1, "b": 2, "c": {"d": 4}}';  
mysql> SELECT JSON_CONTAINS_PATH(@j, 'one', '$.a', '$.e');  
+---------------------------------------------+  
| JSON_CONTAINS_PATH(@j, 'one', '$.a', '$.e') |  
+---------------------------------------------+  
|                                           1 |  
+---------------------------------------------+  
mysql> SELECT JSON_CONTAINS_PATH(@j, 'all', '$.a', '$.e');  
+---------------------------------------------+  
| JSON_CONTAINS_PATH(@j, 'all', '$.a', '$.e') |  
+---------------------------------------------+  
|                                           0 |  
+---------------------------------------------+  
mysql> SELECT JSON_CONTAINS_PATH(@j, 'one', '$.c.d');  
+----------------------------------------+  
| JSON_CONTAINS_PATH(@j, 'one', '$.c.d') |  
+----------------------------------------+  
|                                      1 |  
+----------------------------------------+  
mysql> SELECT JSON_CONTAINS_PATH(@j, 'one', '$.a.d');  
+----------------------------------------+  
| JSON_CONTAINS_PATH(@j, 'one', '$.a.d') |  
+----------------------------------------+  
|                                      0 |  
+----------------------------------------+

JSON_EXTRACT(json_doc,path[,path] ...)
Returns data from a JSON document, selected from the parts of the document matched by the path arguments. Returns NULL if any argument isNULL or no paths locate a value in the document. An error occurs if the_jsondoc_ argument is not a valid JSON document or any path argument is not a valid path expression.
The return value consists of all values matched by the_path_ arguments. If it is possible that those arguments could return multiple values, the matched values are autowrapped as an array, in the order corresponding to the paths that produced them. Otherwise, the return value is the single matched value.

mysql> SELECT JSON_EXTRACT('[10, 20, [30, 40]]', '$[1]');  
+--------------------------------------------+  
| JSON_EXTRACT('[10, 20, [30, 40]]', '$[1]') |  
+--------------------------------------------+  
| 20                                         |  
+--------------------------------------------+  
mysql> SELECT JSON_EXTRACT('[10, 20, [30, 40]]', '$[1]', '$[0]');  
+----------------------------------------------------+  
| JSON_EXTRACT('[10, 20, [30, 40]]', '$[1]', '$[0]') |  
+----------------------------------------------------+  
| [20, 10]                                           |  
+----------------------------------------------------+  
mysql> SELECT JSON_EXTRACT('[10, 20, [30, 40]]', '$[2][*]');  
+-----------------------------------------------+  
| JSON_EXTRACT('[10, 20, [30, 40]]', '$[2][*]') |  
+-----------------------------------------------+  
| [30, 40]                                      |  
+-----------------------------------------------+

MySQL 5.7.9 and later supports the-> operator as shorthand for this function as used with 2 arguments where the left hand side is aJSON column identifier (not an expression) and the right hand side is the JSON path to be matched within the column.

_column_->path
In MySQL 5.7.9 and later, the-> operator serves as an alias for theJSON_EXTRACT() function when used with two arguments, a column identifier on the left and a JSON path (a string literal) on the right that is evaluated against the JSON document (the column value). You can use such expressions in place of column references wherever they occur in SQL statements.
The two SELECT statements shown here produce the same output:

mysql> SELECT c, JSON_EXTRACT(c, "$.id"), g  
     > FROM jemp  
     > WHERE JSON_EXTRACT(c, "$.id") > 1  
     > ORDER BY JSON_EXTRACT(c, "$.name");  
+-------------------------------+-----------+------+  
| c                             | c->"$.id" | g    |  
+-------------------------------+-----------+------+  
| {"id": "3", "name": "Barney"} | "3"       |    3 |  
| {"id": "4", "name": "Betty"}  | "4"       |    4 |  
| {"id": "2", "name": "Wilma"}  | "2"       |    2 |  
+-------------------------------+-----------+------+  
3 rows in set (0.00 sec)  
mysql> SELECT c, c->"$.id", g  
     > FROM jemp  
     > WHERE c->"$.id" > 1  
     > ORDER BY c->"$.name";  
+-------------------------------+-----------+------+  
| c                             | c->"$.id" | g    |  
+-------------------------------+-----------+------+  
| {"id": "3", "name": "Barney"} | "3"       |    3 |  
| {"id": "4", "name": "Betty"}  | "4"       |    4 |  
| {"id": "2", "name": "Wilma"}  | "2"       |    2 |  
+-------------------------------+-----------+------+  
3 rows in set (0.00 sec)

This functionality is not limited toSELECT, as shown here:

mysql> ALTER TABLE jemp ADD COLUMN n INT;  
Query OK, 0 rows affected (0.68 sec)  
Records: 0  Duplicates: 0  Warnings: 0  
mysql> UPDATE jemp SET n=1 WHERE c->"$.id" = "4";  
Query OK, 1 row affected (0.04 sec)  
Rows matched: 1  Changed: 1  Warnings: 0  
mysql> SELECT c, c->"$.id", g, n  
     > FROM jemp  
     > WHERE JSON_EXTRACT(c, "$.id") > 1  
     > ORDER BY c->"$.name";  
+-------------------------------+-----------+------+------+  
| c                             | c->"$.id" | g    | n    |  
+-------------------------------+-----------+------+------+  
| {"id": "3", "name": "Barney"} | "3"       |    3 | NULL |  
| {"id": "4", "name": "Betty"}  | "4"       |    4 |    1 |  
| {"id": "2", "name": "Wilma"}  | "2"       |    2 | NULL |  
+-------------------------------+-----------+------+------+  
3 rows in set (0.00 sec)  
mysql> DELETE FROM jemp WHERE c->"$.id" = "4";  
Query OK, 1 row affected (0.04 sec)  
mysql> SELECT c, c->"$.id", g, n  
     > FROM jemp  
     > WHERE JSON_EXTRACT(c, "$.id") > 1  
     > ORDER BY c->"$.name";  
+-------------------------------+-----------+------+------+  
| c                             | c->"$.id" | g    | n    |  
+-------------------------------+-----------+------+------+  
| {"id": "3", "name": "Barney"} | "3"       |    3 | NULL |  
| {"id": "2", "name": "Wilma"}  | "2"       |    2 | NULL |  
+-------------------------------+-----------+------+------+  
2 rows in set (0.00 sec)

(See Indexing a Generated Column to Provide a JSON Column Index, for the statements used to create and populate the table just shown.)
This also works with JSON array values, as shown here:

mysql> CREATE TABLE tj10 (a JSON, b INT);  
Query OK, 0 rows affected (0.26 sec)  
mysql> INSERT INTO tj10  
     > VALUES ("[3,10,5,17,44]", 33), ("[3,10,5,17,[22,44,66]]", 0);  
Query OK, 1 row affected (0.04 sec)  
mysql> SELECT a->"$[4]" FROM tj10;  
+--------------+  
| a->"$[4]"    |  
+--------------+  
| 44           |  
| [22, 44, 66] |  
+--------------+  
2 rows in set (0.00 sec)  
mysql> SELECT * FROM tj10 WHERE a->"$[0]" = 3;  
+------------------------------+------+  
| a                            | b    |  
+------------------------------+------+  
| [3, 10, 5, 17, 44]           |   33 |  
| [3, 10, 5, 17, [22, 44, 66]] |    0 |  
+------------------------------+------+  
2 rows in set (0.00 sec)

Nested arrays are supported. An expression using-> evaluates as NULL if no matching key is found in the target JSON document, as shown here:

mysql> SELECT * FROM tj10 WHERE a->"$[4][1]" IS NOT NULL;  
+------------------------------+------+  
| a                            | b    |  
+------------------------------+------+  
| [3, 10, 5, 17, [22, 44, 66]] |    0 |  
+------------------------------+------+  
mysql> SELECT a->"$[4][1]" FROM tj10;  
+--------------+  
| a->"$[4][1]" |  
+--------------+  
| NULL         |  
| 44           |  
+--------------+  
2 rows in set (0.00 sec)

This is the same behavior as seen in such cases when usingJSON_EXTRACT():

mysql> SELECT JSON_EXTRACT(a, "$[4][1]") FROM tj10;  
+----------------------------+  
| JSON_EXTRACT(a, "$[4][1]") |  
+----------------------------+  
| NULL                       |  
| 44                         |  
+----------------------------+  
2 rows in set (0.00 sec)

_column_->>path
This is an improved, unquoting extraction operator available in MySQL 5.7.13 and later. Whereas the-> operator simply extracts a value, the->> operator in addition unquotes the extracted result. In other words, given aJSON column value_column_ and a path expression_path_ (a string literal), the following three expressions return the same value:
- JSON_UNQUOTE( JSON_EXTRACT(column,path) )
- JSON_UNQUOTE(_`column`_ -> _`path`_)
- _`column`_->>_`path`_
  The ->> operator can be used whereverJSON_UNQUOTE(JSON_EXTRACT()) would be allowed. This includes (but is not limited to)SELECT lists, WHERE andHAVING clauses, and ORDER BY and GROUP BY clauses.
  The next few statements demonstrate some->> operator equivalences with other expressions in the mysql client:

mysql> SELECT * FROM jemp WHERE g > 2;  
+-------------------------------+------+  
| c                             | g    |  
+-------------------------------+------+  
| {"id": "3", "name": "Barney"} |    3 |  
| {"id": "4", "name": "Betty"}  |    4 |  
+-------------------------------+------+  
2 rows in set (0.01 sec)  
mysql> SELECT c->'$.name' AS name  
    ->     FROM jemp WHERE g > 2;  
+----------+  
| name     |  
+----------+  
| "Barney" |  
| "Betty"  |  
+----------+  
2 rows in set (0.00 sec)  
mysql> SELECT JSON_UNQUOTE(c->'$.name') AS name  
    ->     FROM jemp WHERE g > 2;  
+--------+  
| name   |  
+--------+  
| Barney |  
| Betty  |  
+--------+  
2 rows in set (0.00 sec)  
mysql> SELECT c->>'$.name' AS name  
    ->     FROM jemp WHERE g > 2;  
+--------+  
| name   |  
+--------+  
| Barney |  
| Betty  |  
+--------+  
2 rows in set (0.00 sec)

See Indexing a Generated Column to Provide a JSON Column Index, for the SQL statements used to create and populate thejemp table in the set of examples just shown.
This operator can also be used with JSON arrays, as shown here:

mysql> CREATE TABLE tj10 (a JSON, b INT);  
Query OK, 0 rows affected (0.26 sec)  
mysql> INSERT INTO tj10 VALUES  
    ->     ('[3,10,5,"x",44]', 33),  
    ->     ('[3,10,5,17,[22,"y",66]]', 0);  
Query OK, 2 rows affected (0.04 sec)  
Records: 2  Duplicates: 0  Warnings: 0  
mysql> SELECT a->"$[3]", a->"$[4][1]" FROM tj10;  
+-----------+--------------+  
| a->"$[3]" | a->"$[4][1]" |  
+-----------+--------------+  
| "x"       | NULL         |  
| 17        | "y"          |  
+-----------+--------------+  
2 rows in set (0.00 sec)  
mysql> SELECT a->>"$[3]", a->>"$[4][1]" FROM tj10;  
+------------+---------------+  
| a->>"$[3]" | a->>"$[4][1]" |  
+------------+---------------+  
| x          | NULL          |  
| 17         | y             |  
+------------+---------------+  
2 rows in set (0.00 sec)

As with->, the ->> operator is always expanded in the output of EXPLAIN, as the following example demonstrates:

mysql> EXPLAIN SELECT c->>'$.name' AS name  
    ->     FROM jemp WHERE g > 2\G  
*************************** 1. row ***************************  
           id: 1  
  select_type: SIMPLE  
        table: jemp  
   partitions: NULL  
         type: range  
possible_keys: i  
          key: i  
      key_len: 5  
          ref: NULL  
         rows: 2  
     filtered: 100.00  
        Extra: Using where  
1 row in set, 1 warning (0.00 sec)  
mysql> SHOW WARNINGS\G  
*************************** 1. row ***************************  
  Level: Note  
   Code: 1003  
Message: /* select#1 */ select  
json_unquote(json_extract(`jtest`.`jemp`.`c`,'$.name')) AS `name` from  
`jtest`.`jemp` where (`jtest`.`jemp`.`g` > 2)  
1 row in set (0.00 sec)

This is similar to how MySQL expands the-> operator in the same circumstances.
The ->> operator was added in MySQL 5.7.13.

JSON_KEYS(json_doc[,path])
Returns the keys from the top-level value of a JSON object as a JSON array, or, if a path argument is given, the top-level keys from the selected path. Returns NULL if any argument isNULL, the_jsondoc_ argument is not an object, or path, if given, does not locate an object. An error occurs if the_jsondoc_ argument is not a valid JSON document or the path argument is not a valid path expression or contains a* or ** wildcard.
The result array is empty if the selected object is empty. If the top-level value has nested subobjects, the return value does not include keys from those subobjects.

mysql> SELECT JSON_KEYS('{"a": 1, "b": {"c": 30}}');  
+---------------------------------------+  
| JSON_KEYS('{"a": 1, "b": {"c": 30}}') |  
+---------------------------------------+  
| ["a", "b"]                            |  
+---------------------------------------+  
mysql> SELECT JSON_KEYS('{"a": 1, "b": {"c": 30}}', '$.b');  
+----------------------------------------------+  
| JSON_KEYS('{"a": 1, "b": {"c": 30}}', '$.b') |  
+----------------------------------------------+  
| ["c"]                                        |  
+----------------------------------------------+

JSON_SEARCH(json_doc,one_or_all,search_str[,escape_char[,path] ...])
Returns the path to the given string within a JSON document. Returns NULL if any of the_jsondoc,searchstr, orpath_ arguments areNULL; no path exists within the document; or_searchstr_ is not found. An error occurs if the jsondoc argument is not a valid JSON document, any path argument is not a valid path expression,oneorall is not'one' or 'all', or_escapechar_ is not a constant expression.
The oneorall argument affects the search as follows:
- 'one': The search terminates after the first match and returns one path string. It is undefined which match is considered first.
- 'all': The search returns all matching path strings such that no duplicate paths are included. If there are multiple strings, they are autowrapped as an array. The order of the array elements is undefined.
  Within the searchstr search string argument, the % and _ characters work as for the LIKE operator: % matches any number of characters (including zero characters), and_ matches exactly one character.
  To specify a literal % or_ character in the search string, precede it by the escape character. The default is\ if the_escapechar_ argument is missing orNULL. Otherwise,escapechar must be a constant that is empty or one character.
  For more information about matching and escape character behavior, see the description ofLIKE inSection 12.8.1, “String Comparison Functions and Operators”. For escape character handling, a difference from theLIKE behavior is that the escape character for JSON_SEARCH() must evaluate to a constant at compile time, not just at execution time. For example, ifJSON_SEARCH() is used in a prepared statement and the_escapechar_ argument is supplied using a ? parameter, the parameter value might be constant at execution time, but is not at compile time.
  searchstr and_path_ are always interpeted as utf8mb4 strings, regardless of their actual encoding. This is a known issue which is fixed in MySQL 8.0 ( Bug #32449181).

mysql> SET @j = '["abc", [{"k": "10"}, "def"], {"x":"abc"}, {"y":"bcd"}]';  
mysql> SELECT JSON_SEARCH(@j, 'one', 'abc');  
+-------------------------------+  
| JSON_SEARCH(@j, 'one', 'abc') |  
+-------------------------------+  
| "$[0]"                        |  
+-------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', 'abc');  
+-------------------------------+  
| JSON_SEARCH(@j, 'all', 'abc') |  
+-------------------------------+  
| ["$[0]", "$[2].x"]            |  
+-------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', 'ghi');  
+-------------------------------+  
| JSON_SEARCH(@j, 'all', 'ghi') |  
+-------------------------------+  
| NULL                          |  
+-------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10');  
+------------------------------+  
| JSON_SEARCH(@j, 'all', '10') |  
+------------------------------+  
| "$[1][0].k"                  |  
+------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10', NULL, '$');  
+-----------------------------------------+  
| JSON_SEARCH(@j, 'all', '10', NULL, '$') |  
+-----------------------------------------+  
| "$[1][0].k"                             |  
+-----------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10', NULL, '$[*]');  
+--------------------------------------------+  
| JSON_SEARCH(@j, 'all', '10', NULL, '$[*]') |  
+--------------------------------------------+  
| "$[1][0].k"                                |  
+--------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10', NULL, '$**.k');  
+---------------------------------------------+  
| JSON_SEARCH(@j, 'all', '10', NULL, '$**.k') |  
+---------------------------------------------+  
| "$[1][0].k"                                 |  
+---------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10', NULL, '$[*][0].k');  
+-------------------------------------------------+  
| JSON_SEARCH(@j, 'all', '10', NULL, '$[*][0].k') |  
+-------------------------------------------------+  
| "$[1][0].k"                                     |  
+-------------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10', NULL, '$[1]');  
+--------------------------------------------+  
| JSON_SEARCH(@j, 'all', '10', NULL, '$[1]') |  
+--------------------------------------------+  
| "$[1][0].k"                                |  
+--------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '10', NULL, '$[1][0]');  
+-----------------------------------------------+  
| JSON_SEARCH(@j, 'all', '10', NULL, '$[1][0]') |  
+-----------------------------------------------+  
| "$[1][0].k"                                   |  
+-----------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', 'abc', NULL, '$[2]');  
+---------------------------------------------+  
| JSON_SEARCH(@j, 'all', 'abc', NULL, '$[2]') |  
+---------------------------------------------+  
| "$[2].x"                                    |  
+---------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%a%');  
+-------------------------------+  
| JSON_SEARCH(@j, 'all', '%a%') |  
+-------------------------------+  
| ["$[0]", "$[2].x"]            |  
+-------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%b%');  
+-------------------------------+  
| JSON_SEARCH(@j, 'all', '%b%') |  
+-------------------------------+  
| ["$[0]", "$[2].x", "$[3].y"]  |  
+-------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%b%', NULL, '$[0]');  
+---------------------------------------------+  
| JSON_SEARCH(@j, 'all', '%b%', NULL, '$[0]') |  
+---------------------------------------------+  
| "$[0]"                                      |  
+---------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%b%', NULL, '$[2]');  
+---------------------------------------------+  
| JSON_SEARCH(@j, 'all', '%b%', NULL, '$[2]') |  
+---------------------------------------------+  
| "$[2].x"                                    |  
+---------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%b%', NULL, '$[1]');  
+---------------------------------------------+  
| JSON_SEARCH(@j, 'all', '%b%', NULL, '$[1]') |  
+---------------------------------------------+  
| NULL                                        |  
+---------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%b%', '', '$[1]');  
+-------------------------------------------+  
| JSON_SEARCH(@j, 'all', '%b%', '', '$[1]') |  
+-------------------------------------------+  
| NULL                                      |  
+-------------------------------------------+  
mysql> SELECT JSON_SEARCH(@j, 'all', '%b%', '', '$[3]');  
+-------------------------------------------+  
| JSON_SEARCH(@j, 'all', '%b%', '', '$[3]') |  
+-------------------------------------------+  
| "$[3].y"                                  |  
+-------------------------------------------+

For more information about the JSON path syntax supported by MySQL, including rules governing the wildcard operators* and **, seeJSON Path Syntax.