Using JSON_MODIFY To Modify Existing JSON

Jovan Popovic shows off the JSON_MODIFY function in SQL Server:

Recently I found this question on stack overflow. The problem was in appending a new JSON object to the existing JSON array:

UPDATE TheTable
SET TheJSON = JSON_MODIFY(TheJSON, 'append $', N'{"id": 3, "name": "Three"}')
WHERE Condition = 1;

JSON_MODIFY function should take the array value from TheJSON column (the first argument), append the third argument into the first argument, and write the appended array back in TheJSON column.

However, the unexpected results in this case is the fact that JSON_MODIFY didn’t appended a JSON object {"id": 3, "name": "Three"}to the array. Instead, JSON_MODIFY appended a new JSON string literal  "{\"id\": 3, \"name\": \"Three\"}" to the end of the array.

This might be surprising result if you don’t know how JSON_MODIFY function works.

Read on to see how JSON_MODIFY works and why this doesn’t quite do what the poster thought.

Related Posts

Cannot Rollback TRUNCATE In Redshift

Derik Hammer notes that you cannot rollback a TRUNCATE TABLE operation in Redshift: In SQL Server, or PostgreSQL for that matter, the TRUNCATE command is allowed in a transaction and it will commit or rollback like any other DML operation. In all of the scripts, below, I will do the following. Check my row counts Begin a transaction […]

Read More

Valid WAITFOR Data Types

Dave Mason investigates the valid data types you can use as inputs for WAITFOR: There are certain design patterns in T-SQL that give me pause. They may not be “code smells” per se, but when I encounter them I find myself thinking “there’s got to be a more sensible way to accomplish this”. WAITFOR DELAY is one […]

Read More

Categories

December 2017
MTWTFSS
« Nov Jan »
 123
45678910
11121314151617
18192021222324
25262728293031