I've got a longtext field in my MySQL database that contains JSON strings. I'd like to be able to update only one row in the string rather than have to reinsert the entire thing updated.
How can I do that? I'm using Laravel but could do a raw query if needed.
(This is the first time I'm using JSON, so if I'm not using the right terminolgoy, forgive me.)
Your column needs to be of json type. then you can use the JSON_SET to set a aprticular json key in your payload.
example :
update table SETjson_column= JSON_SET(json_column, '$.\"$key\"' , 'foo') where id = 1;
Related
So I have three databases - an Oracle one, SQL Server one, and a Postgres one. I have a table that has two columns: name, and value, both are texts. The value is a stringified JSON object. I need to update the nested value.
This is what I currently have:
name: 'MobilePlatform',
value:
'{
"iosSupported":true,
"androidSupported":false,
}'
I want to add {"enableTwoFactorAuth": false} into it.
In PostgreSQL you should be able to do this:
UPDATE mytable
SET MobilePlatform = jsonb_set(MobilePlatform::jsonb, '{MobilePlatform,enableTwoFactorAuth}', 'false');
In Postgres, the plain concatenation operator || for jsonb could do it:
UPDATE mytable
SET value = value::jsonb || '{"enableTwoFactorAuth":false}'::jsonb
WHERE name = 'MobilePlatform';
If a top-level key "enableTwoFactorAuth" already exists, it is replaced. So it's an "upsert" really.
Or use jsonb_set() for manipulating nested values.
The cast back to text works implicitly as assignment cast. (Results in standard format; any insignificant whitespace is removed effectively.)
If the content is valid JSON, the storage type should be json to begin with. In Postges, jsonb would be preferable as it's easier to manipulate, but that's not directly portable to the other two RDBMS mentioned.
(Or, possibly, a normalized design without JSON altogether.)
For ORACLE 21
update mytable
set json_col = json_transform(
json_col,
INSERT '$.value.enableTwoFactorAuth' = 'false'
)
where json_exists(json_col, '$?(#.name == "MobilePlatform")')
;
With json_col being JSON or VARCHAR2|CLOB column with IS JSON constraint.
(but must be JSON if you want a multivalue index on json_value.name:
create multivalue index ix_json_col_name on mytable t ( t.json_col.name.string() );
)
Two of the databases you are using support JSON data type, so it doesn't make sense to have them as stringified JSON object in a Text column.
Oracle: https://docs.oracle.com/en/database/oracle/oracle-database/21/adjsn/json-in-oracle-database.html
PostgreSQL: https://www.postgresql.org/docs/current/datatype-json.html
Apart from these, MSSQL Server also provides methods to work with JSON data type.
MS SQL Server: https://learn.microsoft.com/en-us/sql/relational-databases/json/json-data-sql-server?view=sql-server-ver16
Using a JSON type column in any of the above databases would enable you to use their JSON functions to perform the tasks that you are looking for.
If you've to use Text only then you can use replace to add the key-value pair at the end of your JSON
update dataTable set value = REPLACE(value, '}',",\"enableTwoFactorAuth\": false}") where name = 'MobilePlatform'
Here dataTable is the name of table.
The cleaner and less riskier way would be connect to db using the application and use JSON methods such as JSON.parse in Javascript and JSON.loads in Python. This would give you the JSON object (dictionary in case of Python) to work on. You can look for similar methods in other languages as well.
But i would suggest, if possible use JSON columns instead of Text to store the JSON value wherever possible.
I have a JSON array in the MySQL payment table details column. I need to update a single value of this JSON array. What is the procedure to update JSON using MySQL?
JSON Array
{"items":[{"ca_id":18,"appointment_date":"2018-09-15 15:00:00","service_name":"Software Installation / Up-gradation","service_price":165}],"coupon":{"code":"GSSPECIAL","discount":"10","deduction":"0.00"},"subtotal":{"price":165,"deposit":0},"tax_in_price":"included","adjustments":[{"reason":"Over-time","amount":"20","tax":"0"}]}
I need to update the appointment _date 2018-09-15 15:00:00 to 2018-09-28 15:00:00.
Here is a pure MySQL JSON way of doing this:
UPDATE yourTable
SET col = JSON_REPLACE(col, '$.items[0].appointment_date', '2018-09-28 15:00:00');
The best I could come up with is to address the first element of the JSON array called items, and then update the appointment_date field in that array element.
Here is a demo showing that the JSON replacement syntax/logic is working:
Demo
But, you could equally as well have done this JSON work in your PHP layer. It might make more sense to do this in PHP.
If you want to do this in php then, steps to follow:
Select the respective column from the table
Use json_decode to convert the string to array
Now you have the json object, apply your modifications
Use json_encode to convert your json object back to string
Save this string in table
I'm trying to select a key from my db and set its value in a json column with postgres keys are finishing with "_alert".
So in my bd I have a column named data as a json and i just want the keys finishing with "_alert" like "ram_alert", "temperatures_alert", "disk_alert", "cpu_alert".
So I need to get the key and the value to compare with the data I have in my backend app to validate if I need to update the value or dont.
How to do this?
I get all the keys doing select json_object_keys(data) from devices but how to get the key/value pair.. is there a way to use the "like" expression here?
First off, note that your current query will only work if you have one tuple in your 'devices' table. Try inserting another row and you'll get:
ERROR: cannot call json_object_keys on an array
If you're certain that you're only ever going to have ONE result from this table, then the following query should give you what you want:
SELECT key,value FROM devices,json_each(devices.data) where key ~ '_alert$';
I'd still throw something like "LIMIT 1" onto your query to be safe.
I'm working with mongoDB, and I used a wrapper mongo/Postegres.
Now, I can find my tables and data.
I want to do some statistics but I can't reach objects that got json type in Postgres.
My problem is that I got all the object in json but I need to separate the fields.
I used this :
CREATE FOREIGN TABLE rents( _id NAME, status text, "from" json )
SERVER mongo_server
OPTIONS (database 'tr', collection 'rents');
The field "from" is an object.
I found something like this :
enter code here
but nothing happened
The error (why a screenshot??) means that the data are not in valid json format.
As a first step, you could define the column as type text instead of json. Then querying the foreign table will probably work, and you can see what is actually returned and why PostgreSQL thinks that this is not valid JSON.
Maybe you can create a view on top of the foreign table that converts the value to valid JSON for further processing.
Say I have a text field with JSON data like this:
{
"id": {
"name": "value",
"votes": 0
}
}
Is there a way to write a query which would find id and then would increment votes value?
I know i could just retrieve the JSON data update what I need and reinsert updated version, but i wonder is there a way to do this without running two queries?
UPDATE `sometable`
SET `somefield` = JSON_REPLACE(`somefield`, '$.id.votes', JSON_EXTRACT(`somefield` , '$.id.votes')+1)
WHERE ...
Edit
As of MySQL 5.7.8, MySQL supports a native JSON data type that enables efficient access to data in JSON documents.
JSON_EXTRACT will allow you to access a particular JSON element in a JSON field, while JSON_REPLACE will allow you to update it.
To specify the JSON element you wish to access, use a string with the format
'$.[top element].[sub element].[...]'
So in your case, to access id.votes, use the string '$.id.votes'.
The SQL code above demonstrates putting all this together to increment the value of a JSON field by 1.
I think for a task like this you're stuck using a plain old SELECT followed by an UPDATE (after you parse the JSON, increment the value you want, and then serialize the JSON back).
You should wrap these operations in a single transaction, and if you're using InnoDB then you might also consider using SELECT ... FOR UPDATE : http://dev.mysql.com/doc/refman/5.0/en/innodb-locking-reads.html
This is sort of a tangent, but I thought I'd also mention that this is the type of operation that a NoSQL database like MongoDB is quite good at.