官方文档:JSON Functions
Name | Description |
---|---|
JSON_APPEND() | Append data to JSON document |
JSON_ARRAY() | Create JSON array |
JSON_ARRAY_APPEND() | Append data to JSON document |
JSON_ARRAY_INSERT() | Insert into JSON array |
-> | Return value from JSON column after evaluating path; equivalent to JSON_EXTRACT(). |
JSON_CONTAINS() | Whether JSON document contains specific object at path |
JSON_CONTAINS_PATH() | Whether JSON document contains any data at path |
JSON_DEPTH() | Maximum depth of JSON document |
JSON_EXTRACT() | Return data from JSON document |
->> | Return value from JSON column after evaluating path and unquoting the result; equivalent to JSON_UNQUOTE(JSON_EXTRACT()). |
JSON_INSERT() | Insert data into JSON document |
JSON_KEYS() | Array of keys from JSON document |
JSON_LENGTH() | Number of elements in JSON document |
JSON_MERGE() | Merge JSON documents |
JSON_OBJECT() | Create JSON object |
JSON_QUOTE() | Quote JSON document |
JSON_REMOVE() | Remove data from JSON document |
JSON_REPLACE() | Replace values in JSON document |
JSON_SEARCH() | Path to value within JSON document |
JSON_SET() | Insert data into JSON document |
JSON_TYPE() | Type of JSON value |
JSON_UNQUOTE() | Unquote JSON value |
JSON_VALID() | Whether JSON value is valid |
1. 概述
MySQL里的json分为json array和json object。 $表示整个json对象,在索引数据时用下标(对于json array,从0开始)或键值(对于json object,含有特殊字符的key要用"括起来,比如$."my name")。
例如:[3, {"a": [5, 6], "b": 10}, [99, 100]],那么:
$[0]:3
$[1]: {"a": [5, 6], "b": 10}
$[2] :[99, 100]
$[3] : NULL
$[1].a:[5, 6]
$[1].a[1]:6
$[1].b:10
$[2][0]:99
2. 比较规则
json中的数据可以用 =, <, <=, >, >=, <>, !=, and <=> 进行比较。但json里的数据类型可以是多样的,那么在不同类型之间进行比较时,就有优先级了,高优先级的要大于低优先级的
(可以用JSON_TYPE()函数查看类型)。优先级从高到低如下:
BLOB
BIT
OPAQUE
DATETIME
TIME
DATE
BOOLEAN
ARRAY
OBJECT
STRING
INTEGER, DOUBLE
NULL
3. 常用函数
3.1 创建函数
3.1.1 JSON_ARRAY
JSON_ARRAY(val1,val2,val3...)
生成一个包含指定元素的json数组。
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mysql> SELECT JSON_ARRAY(1, "abc" , NULL , TRUE , CURTIME()); + ---------------------------------------------+ | JSON_ARRAY(1, "abc" , NULL , TRUE , CURTIME()) | + ---------------------------------------------+ | [1, "abc" , null , true , "11:30:24.000000" ] | + ---------------------------------------------+ |
3.1.2 JSON_OBJECT
JSON_OBJECT(key1,val1,key2,val2...)
生成一个包含指定K-V对的json object。如果有key为NULL或参数个数为奇数,则抛错。
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mysql> SELECT JSON_OBJECT( 'id' , 87, 'name' , 'carrot' ); + -----------------------------------------+ | JSON_OBJECT( 'id' , 87, 'name' , 'carrot' ) | + -----------------------------------------+ | { "id" : 87, "name" : "carrot" } | + -----------------------------------------+ |
3.1.3 JSON_QUOTE
JSON_QUOTE(json_val)
将json_val用"号括起来。
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mysql> SELECT JSON_QUOTE( 'null' ), JSON_QUOTE( '"null"' ); + --------------------+----------------------+ | JSON_QUOTE( 'null' ) | JSON_QUOTE( '"null"' ) | + --------------------+----------------------+ | "null" | ""null"" | + --------------------+----------------------+ mysql> SELECT JSON_QUOTE( '[1, 2, 3]' ); + -------------------------+ | JSON_QUOTE( '[1, 2, 3]' ) | + -------------------------+ | "[1, 2, 3]" | + -------------------------+ |
3.1.4 CONVERT
CONVERT(json_string,JSON)
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mysql> select CONVERT ( '{"mail": "amy@gmail.com", "name": "Amy"}' ,JSON); + ----------------------------------------------------------+ | CONVERT ( '{"mail": "amy@gmail.com", "name": "Amy"}' ,JSON) | + ----------------------------------------------------------+ | { "mail" : "amy@gmail.com" , "name" : "Amy" } | + ----------------------------------------------------------+ |
3.2 查询函数
3.2.1 JSON_CONTAINS
JSON_CONTAINS(json_doc, val[, path])
查询json文档是否在指定path包含指定的数据,包含则返回1,否则返回0。如果有参数为NULL或path不存在,则返回NULL。
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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, '$.c' ) | + -------------------------------+ | 1 | + -------------------------------+ |
3.2.2 JSON_CONTAINS_PATH
JSON_CONTAINS_PATH(json_doc, one_or_all, path[, path] ...)
查询是否存在指定路径,存在则返回1,否则返回0。如果有参数为NULL,则返回NULL。
one_or_all只能取值"one"或"all",one表示只要有一个存在即可;all表示所有的都存在才行。
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mysql> SET @j = '{"a": 1, "b": 2, "c": {"d": 4}}' ; mysql> SELECT JSON_CONTAINS_PATH(@j, 'one' , '$.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' , '$.a.d' ) | + ----------------------------------------+ | 0 | + ----------------------------------------+ |
3.2.3 JSON_EXTRACT
JSON_EXTRACT(json_doc, path[, path] ...)
从json文档里抽取数据。如果有参数有NULL或path不存在,则返回NULL。如果抽取出多个path,则返回的数据封闭在一个json array里。
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mysql> SELECT JSON_EXTRACT( '[10, 20, [30, 40]]' , '$[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]]' , '$[2][*]' ) | + -----------------------------------------------+ | [30, 40] | + -----------------------------------------------+ |
在MySQL 5.7.9+里可以用"->"替代。
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mysql> SELECT c, JSON_EXTRACT(c, "$.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-> "$.id" | g | + -------------------------------+-----------+------+ | { "id" : "3" , "name" : "Barney" } | "3" | 3 | | { "id" : "4" , "name" : "Betty" } | "4" | 4 | | { "id" : "2" , "name" : "Wilma" } | "2" | 2 | + -------------------------------+-----------+------+ 3 rows in set (0.00 sec) |
在MySQL 5.7.13+,还可以用"->>"表示去掉抽取结果的"号,下面三种效果是一样的:
- JSON_UNQUOTE( JSON_EXTRACT(column, path) )
- JSON_UNQUOTE(column -> path)
- column->>path
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mysql> SELECT * FROM jemp WHERE g > 2; + -------------------------------+------+ | c | g | + -------------------------------+------+ | { "id" : "3" , "name" : "Barney" } | 3 | | { "id" : "4" , "name" : "Betty" } | 4 | + -------------------------------+------+ 2 rows in set (0.01 sec) mysql> SELECT c-> '$.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) |
3.2.4 JSON_KEYS
JSON_KEYS(json_doc[, path])
获取json文档在指定路径下的所有键值,返回一个json array。如果有参数为NULL或path不存在,则返回NULL。
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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" ] | + ----------------------------------------------+ |
3.2.5 JSON_SEARCH
JSON_SEARCH(json_doc, one_or_all, search_str[, escape_char[, path] ...])
查询包含指定字符串的paths,并作为一个json array返回。如果有参数为NUL或path不存在,则返回NULL。
- one_or_all:"one"表示查询到一个即返回;"all"表示查询所有。
- search_str:要查询的字符串。 可以用LIKE里的'%'或‘_'匹配。
- path:在指定path下查。
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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]' ) | + -------------------------------------------+ | "$[3].y" | + -------------------------------------------+ |
3.3 修改函数
3.3.1 JSON_APPEND/JSON_ARRAY_APPEND
JSON_ARRAY_APPEND(json_doc, path, val[, path, val] ...)
在指定path的json array尾部追加val。如果指定path是一个json object,则将其封装成一个json array再追加。如果有参数为NULL,则返回NULL。
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mysql> SET @j = '["a", ["b", "c"], "d"]' ; mysql> SELECT JSON_ARRAY_APPEND(@j, '$[1]' , 1); + ----------------------------------+ | JSON_ARRAY_APPEND(@j, '$[1]' , 1) | + ----------------------------------+ | [ "a" , [ "b" , "c" , 1], "d" ] | + ----------------------------------+ mysql> SELECT JSON_ARRAY_APPEND(@j, '$[0]' , 2); + ----------------------------------+ | JSON_ARRAY_APPEND(@j, '$[0]' , 2) | + ----------------------------------+ | [[ "a" , 2], [ "b" , "c" ], "d" ] | + ----------------------------------+ mysql> SELECT JSON_ARRAY_APPEND(@j, '$[1][0]' , 3); + -------------------------------------+ | JSON_ARRAY_APPEND(@j, '$[1][0]' , 3) | + -------------------------------------+ | [ "a" , [[ "b" , 3], "c" ], "d" ] | + -------------------------------------+ mysql> SET @j = '{"a": 1, "b": [2, 3], "c": 4}' ; mysql> SELECT JSON_ARRAY_APPEND(@j, '$.b' , 'x' ); + ------------------------------------+ | JSON_ARRAY_APPEND(@j, '$.b' , 'x' ) | + ------------------------------------+ | { "a" : 1, "b" : [2, 3, "x" ], "c" : 4} | + ------------------------------------+ mysql> SELECT JSON_ARRAY_APPEND(@j, '$.c' , 'y' ); + --------------------------------------+ | JSON_ARRAY_APPEND(@j, '$.c' , 'y' ) | + --------------------------------------+ | { "a" : 1, "b" : [2, 3], "c" : [4, "y" ]} | + --------------------------------------+ mysql> SET @j = '{"a": 1}' ; mysql> SELECT JSON_ARRAY_APPEND(@j, '$' , 'z' ); + ---------------------------------+ | JSON_ARRAY_APPEND(@j, '$' , 'z' ) | + ---------------------------------+ | [{ "a" : 1}, "z" ] | + ---------------------------------+ |
3.3.2 JSON_ARRAY_INSERT
JSON_ARRAY_INSERT(json_doc, path, val[, path, val] ...)
在path指定的json array元素插入val,原位置及以右的元素顺次右移。如果path指定的数据非json array元素,则略过此val;如果指定的元素下标超过json array的长度,则插入尾部。
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mysql> SET @j = '["a", {"b": [1, 2]}, [3, 4]]' ; mysql> SELECT JSON_ARRAY_INSERT(@j, '$[1]' , 'x' ); + ------------------------------------+ | JSON_ARRAY_INSERT(@j, '$[1]' , 'x' ) | + ------------------------------------+ | [ "a" , "x" , { "b" : [1, 2]}, [3, 4]] | + ------------------------------------+ mysql> SELECT JSON_ARRAY_INSERT(@j, '$[100]' , 'x' ); + --------------------------------------+ | JSON_ARRAY_INSERT(@j, '$[100]' , 'x' ) | + --------------------------------------+ | [ "a" , { "b" : [1, 2]}, [3, 4], "x" ] | + --------------------------------------+ mysql> SELECT JSON_ARRAY_INSERT(@j, '$[1].b[0]' , 'x' ); + -----------------------------------------+ | JSON_ARRAY_INSERT(@j, '$[1].b[0]' , 'x' ) | + -----------------------------------------+ | [ "a" , { "b" : [ "x" , 1, 2]}, [3, 4]] | + -----------------------------------------+ mysql> SELECT JSON_ARRAY_INSERT(@j, '$[2][1]' , 'y' ); + ---------------------------------------+ | JSON_ARRAY_INSERT(@j, '$[2][1]' , 'y' ) | + ---------------------------------------+ | [ "a" , { "b" : [1, 2]}, [3, "y" , 4]] | + ---------------------------------------+ mysql> SELECT JSON_ARRAY_INSERT(@j, '$[0]' , 'x' , '$[2][1]' , 'y' ); + ----------------------------------------------------+ | JSON_ARRAY_INSERT(@j, '$[0]' , 'x' , '$[2][1]' , 'y' ) | + ----------------------------------------------------+ | [ "x" , "a" , { "b" : [1, 2]}, [3, 4]] | + ----------------------------------------------------+ |
3.3.3 JSON_INSERT/JSON_REPLACE/JSON_SET
JSON_INSERT(json_doc, path, val[, path, val] ...)
在指定path下插入数据,如果path已存在,则忽略此val(不存在才插入)。
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mysql> SET @j = '{ "a": 1, "b": [2, 3]}' ; mysql> SELECT JSON_INSERT(@j, '$.a' , 10, '$.c' , '[true, false]' ); + ----------------------------------------------------+ | JSON_INSERT(@j, '$.a' , 10, '$.c' , '[true, false]' ) | + ----------------------------------------------------+ | { "a" : 1, "b" : [2, 3], "c" : "[true, false]" } | + ----------------------------------------------------+ |
JSON_REPLACE(json_doc, path, val[, path, val] ...)
替换指定路径的数据,如果某个路径不存在则略过(存在才替换)。如果有参数为NULL,则返回NULL。
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mysql> SET @j = '{ "a": 1, "b": [2, 3]}' ; mysql> SELECT JSON_REPLACE(@j, '$.a' , 10, '$.c' , '[true, false]' ); + -----------------------------------------------------+ | JSON_REPLACE(@j, '$.a' , 10, '$.c' , '[true, false]' ) | + -----------------------------------------------------+ | { "a" : 10, "b" : [2, 3]} | + -----------------------------------------------------+ |
JSON_SET(json_doc, path, val[, path, val] ...)
设置指定路径的数据(不管是否存在)。如果有参数为NULL,则返回NULL。
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mysql> SET @j = '{ "a": 1, "b": [2, 3]}' ; mysql> SELECT JSON_SET(@j, '$.a' , 10, '$.c' , '[true, false]' ); + -------------------------------------------------+ | JSON_SET(@j, '$.a' , 10, '$.c' , '[true, false]' ) | + -------------------------------------------------+ | { "a" : 10, "b" : [2, 3], "c" : "[true, false]" } | + -------------------------------------------------+ mysql> SELECT JSON_INSERT(@j, '$.a' , 10, '$.c' , '[true, false]' ); + ----------------------------------------------------+ | JSON_INSERT(@j, '$.a' , 10, '$.c' , '[true, false]' ) | + ----------------------------------------------------+ | { "a" : 1, "b" : [2, 3], "c" : "[true, false]" } | + ----------------------------------------------------+ mysql> SELECT JSON_REPLACE(@j, '$.a' , 10, '$.c' , '[true, false]' ); + -----------------------------------------------------+ | JSON_REPLACE(@j, '$.a' , 10, '$.c' , '[true, false]' ) | + -----------------------------------------------------+ | { "a" : 10, "b" : [2, 3]} | + -----------------------------------------------------+ |
3.3.4 JSON_MERGE
JSON_MERGE(json_doc, json_doc[, json_doc] ...)
merge多个json文档。规则如下:
- 如果都是json array,则结果自动merge为一个json array;
- 如果都是json object,则结果自动merge为一个json object;
- 如果有多种类型,则将非json array的元素封装成json array再按照规则一进行mege。
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mysql> SELECT JSON_MERGE( '[1, 2]' , '[true, false]' ); + ---------------------------------------+ | JSON_MERGE( '[1, 2]' , '[true, false]' ) | + ---------------------------------------+ | [1, 2, true , false ] | + ---------------------------------------+ mysql> SELECT JSON_MERGE( '{"name": "x"}' , '{"id": 47}' ); + -------------------------------------------+ | JSON_MERGE( '{"name": "x"}' , '{"id": 47}' ) | + -------------------------------------------+ | { "id" : 47, "name" : "x" } | + -------------------------------------------+ mysql> SELECT JSON_MERGE( '1' , 'true' ); + -------------------------+ | JSON_MERGE( '1' , 'true' ) | + -------------------------+ | [1, true ] | + -------------------------+ mysql> SELECT JSON_MERGE( '[1, 2]' , '{"id": 47}' ); + ------------------------------------+ | JSON_MERGE( '[1, 2]' , '{"id": 47}' ) | + ------------------------------------+ | [1, 2, { "id" : 47}] | + ------------------------------------+ |
3.3.5 JSON_REMOVE
JSON_REMOVE(json_doc, path[, path] ...)
移除指定路径的数据,如果某个路径不存在则略过此路径。如果有参数为NULL,则返回NULL。
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mysql> SET @j = '["a", ["b", "c"], "d"]' ; mysql> SELECT JSON_REMOVE(@j, '$[1]' ); + -------------------------+ | JSON_REMOVE(@j, '$[1]' ) | + -------------------------+ | [ "a" , "d" ] | + -------------------------+ |
3.3.6 JSON_UNQUOTE
JSON_UNQUOTE(val)
去掉val的引号。如果val为NULL,则返回NULL。
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mysql> SET @j = '"abc"' ; mysql> SELECT @j, JSON_UNQUOTE(@j); + -------+------------------+ | @j | JSON_UNQUOTE(@j) | + -------+------------------+ | "abc" | abc | + -------+------------------+ mysql> SET @j = '[1, 2, 3]' ; mysql> SELECT @j, JSON_UNQUOTE(@j); + -----------+------------------+ | @j | JSON_UNQUOTE(@j) | + -----------+------------------+ | [1, 2, 3] | [1, 2, 3] | + -----------+------------------+ |
3.4 JSON特性查询
3.4.1 JSON_DEEPTH
JSON_DEPTH(json_doc)
获取json文档的深度。如果参数为NULL,则返回NULL。
空的json array、json object或标量的深度为1。
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mysql> SELECT JSON_DEPTH( '{}' ), JSON_DEPTH( '[]' ), JSON_DEPTH( 'true' ); + ------------------+------------------+--------------------+ | JSON_DEPTH( '{}' ) | JSON_DEPTH( '[]' ) | JSON_DEPTH( 'true' ) | + ------------------+------------------+--------------------+ | 1 | 1 | 1 | + ------------------+------------------+--------------------+ mysql> SELECT JSON_DEPTH( '[10, 20]' ), JSON_DEPTH( '[[], {}]' ); + ------------------------+------------------------+ | JSON_DEPTH( '[10, 20]' ) | JSON_DEPTH( '[[], {}]' ) | + ------------------------+------------------------+ | 2 | 2 | + ------------------------+------------------------+ mysql> SELECT JSON_DEPTH( '[10, {"a": 20}]' ); + -------------------------------+ | JSON_DEPTH( '[10, {"a": 20}]' ) | + -------------------------------+ | 3 | + -------------------------------+ |
3.4.2 JSON_LENGTH
JSON_LENGTH(json_doc[, path])
获取指定路径下的长度。如果参数为NULL,则返回NULL。
长度的计算规则:
- 标量的长度为1;
- json array的长度为元素的个数;
- json object的长度为key的个数。
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mysql> SELECT JSON_LENGTH( '[1, 2, {"a": 3}]' ); + ---------------------------------+ | JSON_LENGTH( '[1, 2, {"a": 3}]' ) | + ---------------------------------+ | 3 | + ---------------------------------+ mysql> SELECT JSON_LENGTH( '{"a": 1, "b": {"c": 30}}' ); + -----------------------------------------+ | JSON_LENGTH( '{"a": 1, "b": {"c": 30}}' ) | + -----------------------------------------+ | 2 | + -----------------------------------------+ mysql> SELECT JSON_LENGTH( '{"a": 1, "b": {"c": 30}}' , '$.b' ); + ------------------------------------------------+ | JSON_LENGTH( '{"a": 1, "b": {"c": 30}}' , '$.b' ) | + ------------------------------------------------+ | 1 | + ------------------------------------------------+ |
3.4.3 JSON_TYPE
JSON_TYPE(json_val)
获取json文档的具体类型。如果参数为NULL,则返回NULL。
3.4.4 JSON_VALID
JSON_VALID(val)
判断val是否为有效的json格式,是为1,不是为0。如果参数为NUL,则返回NULL。
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mysql> SELECT JSON_VALID( '{"a": 1}' ); + ------------------------+ | JSON_VALID( '{"a": 1}' ) | + ------------------------+ | 1 | + ------------------------+ mysql> SELECT JSON_VALID( 'hello' ), JSON_VALID( '"hello"' ); + ---------------------+-----------------------+ | JSON_VALID( 'hello' ) | JSON_VALID( '"hello"' ) | + ---------------------+-----------------------+ | 0 | 1 | + ---------------------+-----------------------+ |
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原文链接:https://www.cnblogs.com/waterystone/p/5626098.html