Oracle JSON api - update single record in json collection - json

Question

I have CLOB field with JSON data :
[
{
"name": "Rahul",
"LName": "Sharma",
"salary": "20000",
"Age": "35"
},
{
"name": "Kunal",
"LName": "Vohra",
"salary": "10000",
"Age": "25"
}
]
and I need update value in only one element of that array, for example in record with name: Kunal I need change salary.
I try json_transform() but with this I transform every field salary to new value.
json_transform(json_field_in_table, SET '$.salary' = 15000)

Answer 1

You may use filter expression in JSON path of json_transform function to update specific objects:
with a(col) as (
select q'$[
{
"name": "Rahul",
"LName": "Sharma",
"salary": "20000",
"Age": "35"
},
{
"name": "Kunal",
"LName": "Vohra",
"salary": "10000",
"Age": "25"
}
]$' from dual
)
select
json_transform(
col,
set '$[*]?(#.name == "Kunal").salary' = '100'
) as res
from a
RES
[{"name":"Rahul","LName":"Sharma","salary":"20000","Age":"35"},{"name":"Kunal","LName":"Vohra","salary":"100","Age":"25"}]
fiddle
Note that "10000" is a string in JSON, numbers should be used without quotes: {"salary: 10000}

Answer 2

You can't use json_transform because json_transform, json_exists... evaluate on the whole JSON document not on pieces of it,
even a json_exists with "'$?(#.name == "Kunal")'" will consider that the whole document matches and then update all "salary" fields.
(https://docs.oracle.com/en/database/oracle/oracle-database/12.2/adjsn/condition-JSON_EXISTS.html#GUID-8A0043D5-95F8-4918-9126-F86FB0E203F0)
but you can:
select json_arrayagg(json_object (
'name' value name,
'LName' value lname,
'salary' value case when name = 'Kunal' then 15000 else salary end,
'Age' value age)) as js
from
json_table(q'~[
{
"name": "Rahul",
"LName": "Sharma",
"salary": "20000",
"Age": "35"
},
{
"name": "Kunal",
"LName": "Vohra",
"salary": "10000",
"Age": "25"
}
]~','$[*]'
columns (
name VARCHAR2(64) path '$.name',
LName VARCHAR2(64) path '$.LName',
salary NUMBER path '$.salary',
age NUMBER path '$.Age'
));