How to Parse Nested JSON in SQL Server

Learn how to effectively parse nested JSON data in SQL Server, ensuring all relevant rows are returned with organized headers.
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How to Parse Nested JSON in SQL Server

In today's data-driven world, handling JSON (JavaScript Object Notation) is becoming increasingly vital for developers and database managers alike. A common challenge when working with JSON in SQL Server is parsing nested structures, particularly when you want to extract all relevant information into an organized table format. In this guide, we will tackle the issue of how to successfully parse nested JSON obtained from an API and store it in a SQL table.

The Problem

Imagine you've retrieved JSON data from an API, and you need to store this data effectively in your SQL Server database. However, when you attempt to parse the JSON, you only get a single row returned instead of the multiple rows you'd expect. The critical headers needed are NAME, JobNum, Water, and Sewer. This can be frustrating, especially when you are uncertain about how to correctly utilize SQL Server's JSON functions like OPENJSON to get the desired result.

Example of JSON Structure

Here's a simplified structure of the JSON data you might encounter:

[[See Video to Reveal this Text or Code Snippet]]

The Solution

To correctly parse the nested JSON and return all relevant rows, we need to modify our SQL query. Here’s how to do it step by step:

1. Loading the JSON Data

First, you must load your JSON data into a SQL variable. This is done using the OPENROWSET function:

[[See Video to Reveal this Text or Code Snippet]]

2. Validate the JSON

Before parsing the JSON, it's a good practice to validate it using the ISJSON function:

[[See Video to Reveal this Text or Code Snippet]]

3. Parse Nested JSON with OPENJSON

Now, this is where we adjust our parsing logic using the OPENJSON function. To correctly fetch all rows, we need to adjust our JSON path as follows:

[[See Video to Reveal this Text or Code Snippet]]

In this updated query:

By moving the path settings inside the WITH clause for the columns, you ensure that the query processes each item in the items array, extracting names and values as needed.

4. Processing the Results

Once you run this query, you should retrieve all rows corresponding to the NAME, JobNum, Water, and Sewer columns from the JSON data. You will now see multiple rows in your result set, each containing the details from the JSON structure.

Conclusion

Parsing nested JSON can seem daunting, but, as we've demonstrated, it is achievable with SQL Server's built-in functions. Make sure to correctly utilize OPENJSON while understanding the structure of your JSON data to extract the required information effectively. With this knowledge, you'll be able to efficiently work with JSON data in your SQL projects.

Got questions or need further clarification? Feel free to drop a comment below!