MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
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. Returns
NULL if any argument is
NULL, 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, use
JSON_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 same
JSON_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 json_doc argument is not a
valid JSON document, any path
argument is not a valid path expression, or
one_or_all is not
'one' or 'all'.
To check for a specific value at a path, use
JSON_CONTAINS() instead.
The return value is 0 if no specified path exists within the
document. Otherwise, the return value depends on the
one_or_all 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 is
NULL or no paths locate a value in the
document. An error occurs if the
json_doc 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 a
JSON column identifier (not an
expression) and the right hand side is the JSON path to be
matched within the column.
In MySQL 5.7.9 and later, the
->
operator serves as an alias for the
JSON_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 to
SELECT, 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 using
JSON_EXTRACT():
mysql> SELECT JSON_EXTRACT(a, "$[4][1]") FROM tj10;
+----------------------------+
| JSON_EXTRACT(a, "$[4][1]") |
+----------------------------+
| NULL |
| 44 |
+----------------------------+
2 rows in set (0.00 sec)
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 a
JSON column value
column and a path expression
path (a string literal), the
following three expressions return the same value:
JSON_UNQUOTE(
column->
path)
column->>path
The ->> operator can be used wherever
JSON_UNQUOTE(JSON_EXTRACT()) would be
allowed. This includes (but is not limited to)
SELECT lists, WHERE and
HAVING 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->>'$.name' AS name->FROM jemp WHERE g > 2;+--------+ | name | +--------+ | Barney | | Betty | +--------+ 2 rows in set (0.00 sec)
See Indexing a Generated Column to Provide a JSON Column Index, for the SQL
statements used to create and populate the
jemp table in the set of examples just
shown.
This operator can also be used with JSON arrays, as shown here:
mysql>CREATE TABLE tj10 (a JSON, b INT);Query OK, 0 rows affected (0.26 sec) mysql>INSERT INTO tj10 VALUES->('[3,10,5,"x",44]', 33),->('[3,10,5,17,[22,"y",66]]', 0);Query OK, 2 rows affected (0.04 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql>SELECT a->"$[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`,'$.name')) AS `name` from `jtest`.`jemp` where (`jtest`.`jemp`.`g` > 2) 1 row in set (0.00 sec)
This is similar to how MySQL expands the
->
operator in the same circumstances.
The ->> operator was added in MySQL
5.7.13.
Returns the keys from the top-level value of a JSON object as
a JSON array, or, if a path
argument is given, the top-level keys from the selected path.
Returns NULL if any argument is
NULL, the
json_doc argument is not an object,
or path, if given, does not locate
an object. An error occurs if the
json_doc argument is not a valid
JSON document or the path argument
is not a valid path expression or contains a
* or ** wildcard.
The result array is empty if the selected object is empty. If the top-level value has nested subobjects, the return value does not include keys from those subobjects.
mysql>SELECT JSON_KEYS('{"a": 1, "b": {"c": 30}}');+---------------------------------------+ | JSON_KEYS('{"a": 1, "b": {"c": 30}}') | +---------------------------------------+ | ["a", "b"] | +---------------------------------------+ mysql>SELECT JSON_KEYS('{"a": 1, "b": {"c": 30}}', '$.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
json_doc,
search_str, or
path arguments are
NULL; no path
exists within the document; or
search_str is not found. An error
occurs if the json_doc argument is
not a valid JSON document, any path
argument is not a valid path expression,
one_or_all is not
'one' or 'all', or
escape_char is not a constant
expression.
The one_or_all 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 search_str 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
escape_char argument is missing or
NULL. Otherwise,
escape_char must be a constant that
is empty or one character.
For more information about matching and escape character
behavior, see the description of
LIKE in
Section 12.8.1, “String Comparison Functions and Operators”. For escape
character handling, a difference from the
LIKE behavior is that the escape
character for JSON_SEARCH()
must evaluate to a constant at compile time, not just at
execution time. For example, if
JSON_SEARCH() is used in a
prepared statement and the
escape_char argument is supplied
using a ? parameter, the parameter value
might be constant at execution time, but is not at compile
time.
search_str 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 **, see
JSON Path Syntax.