I have a table with two labels: id INT and value JSONB. In value I have a json object props with keys id_1, id_2, and so on, with their respective values.
Is there a way to count the rows where the JSON object props has a specific key, such as id_1?
In this example, there should be two results: rows 1 and 4.
id | value
1 | {"name": "Jhon", "props": {"id_1": {"role": "role1", "class": "class1"}, "id_2": {"role": "role2", "class": "class2"}}}
2 | {"name": "Frank", "role": ["role1", "role2"]}
3 | {"name": "Bob", "props": {"id_3": {"role": "role3", "class": "class3"}, "id_4": {"role": "role4"}}}
4 | {"name": "Carl", "props": {"id_5": {"role": "role5", "class": "class5"}, "id_1": {"class": "class6"}}}
I tried something like this, but to make it work, I have to also specify the value, but the value could change for every row. For example, with this query, I only get one row back.
SELECT count(value)
FROM "myTable"
where value->'props' ->> 'id_1' = '{"role": "role1", "class": "class1"}'
Try this-
SELECT COUNT(z.*) FROM (
SELECT id, value->'props'->>'id_1' as val FROM "myTable" ) z WHERE z.val
IS NOT NULL
Use the ? operator to test whether a key exists, regardless of value.
SELECT count(*)
FROM "myTable"
where value -> 'props' ? 'id_1
Related
I have searched and can't seem to find somewhere doing exactly what I am trying.
I have a json similar to as follows in multiple rows in my database:
{
"date": "0001-01-01T00:00:00",
"details": {
"detail": [
{
"item": "11",
"value": "xt"
},
{
"item": "12",
"value": "xy"
},
{
"item": "13",
"value": "xz"
},
{
"item": "14",
"value": "zz"
}
]
}
}
I want to do sql that does this:
select ID
jsonColumn.value where item=11 as X
jsonColumn.value where item=12 as Y
from tbl
So I have results like this
----------------------
|ID |X |Y |
----------------------
|1 |xt |xy |
----------------------
I have tried using JSONVALUE but I seem to need to do it by the array item number like this:
'$.details.detail[3].value'
which doesn't really work
I have also tried this:
SELECT id, x.item, x.value
FROM
tbl F
CROSS APPLY (select *
FROM OPENJSON(F.Json,'$.details.detail')
CROSS APPLY OPENJSON(value)
WITH (item NVARCHAR(25) '$.item',
value NVARCHAR(max) '$.value') As x
where F.ID=55
Which I can use to print out all the items and values but then I'd have to query each separately again.
Is there a way of combining the two in to one big query that won't be completely inefficient?
Seems what you want is a pivot. I personally use conditional aggregation over the far more restrictive PIVOT operator. The JSON you supplied was invalid, so I took some liberties correcting it in my sandbox environment:
SELECT --ID,
MAX(CASE d.item WHEN 11 THEN d.[value] END) AS X,
MAX(CASE d.item WHEN 12 THEN d.[value] END) AS Y
FROM (VALUES(#JSON))V(J) --Your Table
CROSS APPLY OPENJSON(V.J,'$.details')
WITH (detail nvarchar(MAX) AS JSON ) OJ
CROSS APPLY OPENJSON(OJ.detail)
WITH(item int,
[value] nvarchar(2)) d;
If you are using this against a table, and not limiting the data to a single row, you'll need to also add a GROUP BY clause on the relevant columns (ID?).
Consider this table:
DROP TABLE IF EXISTS `example`;
CREATE TABLE `example` (
`id` int NOT NULL AUTO_INCREMENT,
`content` json NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;
And these rows:
INSERT INTO example(content)
VALUES (
'[ { "date": "1617210148", "name": "John", "status": "0" },
{ "date": "1617210148", "name": "Jack", "status": "0" },
{ "date": "1617210148", "name": "Henry", "status": "0" }]'
);
I'd like to update the value of the key status where name = Jack to 1
The result would be:
{ "date": "1617210148", "name": "Jack", "status": "1" }
How can I do this using JSON_REPLACE() or JSON_SET() in a SQL query (I'm aiming for a partial update since I'm using MySQL 8.0.25)?
This is very awkward, nearly impossible with MySQL's JSON functions.
You can use JSON_REPLACE() or JSON_SET(), but both require that you know the path to the field you want to change. So in this case, we can see that the array element is $[1] but if you didn't know that, you couldn't use this solution.
mysql> select json_pretty(json_replace(content, '$[1].status', '1')) as j
from example\G
*************************** 1. row ***************************
j: [
{
"date": "1617210148",
"name": "John",
"status": "0"
},
{
"date": "1617210148",
"name": "Jack",
"status": "1"
},
{
"date": "1617210148",
"name": "Henry",
"status": "0"
}
]
The question like yours has come up before on Stack Overflow, for example JSON update single value in MySQL table. The solution in that case depends on you knowing which array element your pseudo-record exists in.
You can get the path to a JSON element with JSON_SEARCH(), but you can only search by value, not by a key/value pair. If "Jack" occurs in some other field, that would also be found.
mysql> select json_unquote(json_search(content, 'one', 'Jack')) as path from example;
+-----------+
| path |
+-----------+
| $[1].name |
+-----------+
To search for a key/value pair, you need to use JSON_TABLE() and that requires you upgrade to MySQL 8.0. And that doesn't tell you the path to the element, it only allows you to return a specific row out of the array.
mysql> select j.* from example cross join json_table(content, '$[*]' columns(
date int unsigned path '$.date',
name varchar(10) path '$.name',
status int path '$.status')
) as j where name = 'Jack';
+------------+------+--------+
| date | name | status |
+------------+------+--------+
| 1617210148 | Jack | 0 |
+------------+------+--------+
Here's a trick: You can extract the name field, and that turns into an array of those values:
mysql> select json_extract(content, '$[*].name') as a from example;
+---------------------------+
| a |
+---------------------------+
| ["John", "Jack", "Henry"] |
+---------------------------+
Then you can search that array to get the array position:
mysql> select json_search(json_extract(content, '$[*].name'), 'one', 'Jack') as root from example;
+--------+
| root |
+--------+
| "$[1]" |
+--------+
Some unquoting and adding .status and you can get the full path to the field you want to update:
mysql> select concat(json_unquote(json_search(json_extract(content, '$[*].name'), 'one', 'Jack')), '.status') as path from example;
+-------------+
| path |
+-------------+
| $[1].status |
+-------------+
Now use it in a JSON_SET() call:
mysql> select json_pretty(
json_set(content,
concat(json_unquote(json_search(json_extract(content, '$[*].name'), 'one', 'Jack')), '.status'),
'1')) as newcontent
from example\G
*************************** 1. row ***************************
newcontent: [
{
"date": "1617210148",
"name": "John",
"status": "0"
},
{
"date": "1617210148",
"name": "Jack",
"status": "1"
},
{
"date": "1617210148",
"name": "Henry",
"status": "0"
}
]
Using this in an UPDATE looks like this:
mysql> update example set content = json_set(content, concat(json_unquote(json_search(json_extract(content, '$[*].name'), 'one', 'Jack')), '.status'), '1');
That's a long way to go. Now compare how difficult that is to:
UPDATE content SET status = 1 WHERE name = 'Jack';
Storing data in a JSON document when you eventually want to use SQL expressions to search or update individual fields within the JSON document is a costly mistake. It increases the complexity of any code you write to do it, and the developer who needs to take over maintenance of your code after you have moved on to another project will curse your name.
I have started using MySQL 8 and trying to update JSON data type in a mysql table
My table t1 looks as below:
# id group names
1100000 group1 [{"name": "name1", "type": "user"}, {"name": "name2", "type": "user"}, {"name": "techDept", "type": "dept"}]
I want to add user3 to the group1 and written below query:
update t1 set names = JSON_SET(names, "$.name", JSON_ARRAY('user3')) where group = 'group1';
However, the above query is not working
I suppose you want the result to be:
[{"name": "name1", "type": "user"}, {"name": "name2", "type": "user"}, {"name": "techDept", "type": "dept"}, {"name": "user3", "type": "user"}]
This should work:
UPDATE t1 SET names = JSON_ARRAY_APPEND(names, '$', JSON_OBJECT('name', 'user3', 'type', 'user'))
WHERE `group` = 'group1';
But it's not clear why you are using JSON at all. The normal way to store this data would be to create a second table for group members:
CREATE TABLE group_members (
member_id INT PRIMARY KEY,
`group` VARCHAR(10) NOT NULL,
member_type ENUM('user','dept') NOT NULL DEFAULT 'user',
name VARCHAR(10) NOT NULL
);
Then store one per row.
Adding a new member would be like:
INSERT INTO group_members
SET `group` = 'group1', name = 'user3';
So much simpler than using JSON!
A PostgreSQL instance stores data in JSONB format:
CREATE TABLE myschema.mytable (
id BIGSERIAL PRIMARY KEY,
data JSONB NOT NULL
)
The data array might contain objects like:
{
"observations": {
"temperature": {
"type": "float",
"unit": "C",
"value": "23.1"
},
"pressure": {
"type": "float",
"unit": "mbar",
"value": "1011.3"
}
}
}
A selected row should be returned as key-value pairs in a format like:
temperature,type,float,value,23.1,unit,C,pressure,type,float,value,1011.3,unit,mbar
The following query returns at least each object, while still JSON:
SELECT id, value FROM mytable JOIN jsonb_each_text(mytable.data->'observations') ON true;
1 | {"type": "float", "unit": "mbar", "value": 1140.5}
1 | {"type": "float", "unit": "C", "value": -0.9}
5 | {"type": "float", "unit": "mbar", "value": "1011.3"}
5 | {"type": "float", "unit": "C", "value": "23.1"}
But the results are splitted and not in text format.
How can I return key-value pairs of all objects in data?
This will flatten the json structure and effectively just concatenate the values, along with the top-level key names (e.g. temperature and pressure), for the expected "depth" level. See if this is what you had in mind.
SELECT
id,
(
SELECT STRING_AGG(conc, ',')
FROM (
SELECT CONCAT_WS(',', key, STRING_AGG(value, ',')) AS conc
FROM (
SELECT key, (jsonb_each_text(value)).value
FROM jsonb_each(data->'observations')
) AS x
GROUP BY key
) AS csv
) AS csv
FROM mytable
Result:
| id | csv |
| --- | --------------------------------------------------- |
| 1 | pressure,float,mbar,1011.3,temperature,float,C,23.1 |
| 2 | pressure,bigint,unk,455,temperature,int,F,45 |
https://www.db-fiddle.com/f/ada5mtMgYn5acshi3WLR7S/0
In MariaDB 10.2.19, I have a table named forms with a column template which always contains a JSON array of objects. Some of these objects will have properties I want to return: name (should always be present), rule, and parameters. How can I return just these three properties from the entire array, but only for objects on which rule is present?
A sample array (formatted for easier viewing):
[{
"label": "Employed?",
"class": "select",
"name": "employed",
"parameters": "Yes",
"rule": "in"
},
{
"label": "Breed of dog?",
"class": "select",
"name": "breed",
"parameters": "spaniel, collie, mix",
"rule": "in"
},
{
"label": "Number",
"class": "text",
"name": "breed"
}]
If you are using MySQL 8.0.4 or later one way is using JSON_TABLE:
mysql> SELECT * FROM foo;
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| data |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| [{"name": "employed", "rule": "in", "class": "select", "label": "Employed?", "parameters": "Yes"}, {"name": "breed", "rule": "in", "class": "select", "label": "Breed of dog?", "parameters": "spaniel, collie, mix"}, {"name": "breed", "class": "text", "label": "Number"}] |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0,00 sec)
mysql> SELECT name, parameters
FROM foo,
JSON_TABLE (
foo.data,
"$[*]" COLUMNS (
name VARCHAR(100) PATH "$.name",
rule VARCHAR(100) PATH "$.rule",
parameters VARCHAR(100) PATH "$.parameters")
) AS t
WHERE rule IS NOT NULL;
+----------+----------------------+
| name | parameters |
+----------+----------------------+
| employed | Yes |
| breed | spaniel, collie, mix |
+----------+----------------------+
2 rows in set (0,00 sec)
https://dev.mysql.com/doc/refman/8.0/en/json-table-functions.html
You can accomplish this by using a dedicated numbers_table table:
SELECT
JSON_VALUE(f.template,CONCAT('$[',n.number,'].name')) AS `name`,
JSON_VALUE(f.template,CONCAT('$[',n.number,'].rule')) AS `rule`,
JSON_VALUE(f.template,CONCAT('$[',n.number,'].parameters')) AS `parameters`
FROM forms AS f
JOIN numbers_table AS n
WHERE
n.number < JSON_LENGTH(f.template) AND
JSON_VALUE(f.template,CONCAT('$[',n.number,'].rule')) IS NOT NULL;
The numbers_table table contains a single column called number which starts at 0 and can be as long as your use cases require (I have 1000 values 0 to 999). It is very useful for extracting each element of a JSON_ARRAY field into its own row.
The first WHERE condition makes sure we only use as many numbers as there are elements in the JSON_ARRAY (template in your case).
The second WHERE condition eliminates the ones that don't have a rule as per your use case.