Accessing an array object from JSON by index-variable in SQL Server

Learn how to access JSON array objects with a variable index in SQL Server using concatenation and OPENJSON.
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Accessing an Array Object from JSON by Index Variable in SQL Server

Working with JSON data can be quite challenging, especially when it comes to accessing array objects by their index using T-SQL variables. Many developers encounter issues when trying to retrieve information dynamically from a JSON array based on a variable index. In this guide, we will explore a common problem and provide effective solutions to navigate this challenge in SQL Server.

The Problem

Consider the following scenario: You've defined a JSON structure in SQL Server that includes an array of addresses within a store object. You want to retrieve the addressType from a specific address in the array using a variable. However, when you attempt to access the JSON array using a variable index, you encounter an error message, such as:

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

This error occurs because SQL Server does not allow direct use of T-SQL variables within the path of the JSON_VALUE() function. Let's take a closer look at how to effectively achieve your goal.

Understanding the JSON Structure

Before diving into the solution, let's review the JSON structure you'll be working with. Here is the JSON example:

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

In this structure, the addresses array contains several objects, and you need to access the addressType of a specific entry using a variable index.

Solution Approaches

Though direct variable integration within the JSON_VALUE() function path is not permitted, there are effective workarounds. Here are two recommended methods:

1. Concatenate the Variable in the Path

If you are using SQL Server 2017 or later, you can dynamically construct the path using the CONCAT() function. Here’s how you can do it:

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

2. Using OPENJSON()

Another approach is to use the OPENJSON() function, which allows for more flexible querying of JSON data. Here’s how you can retrieve the addressType using this method:

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

Result

Using either method will provide you with the expected results. For instance, both approaches will return the addressType:

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

Conclusion

Accessing JSON array objects with a variable index in SQL Server can present some challenges, but with the right techniques, you can successfully retrieve the information you need. Utilizing the CONCAT() function or the OPENJSON() method provides clear and effective solutions, enabling you to work with JSON data dynamically and efficiently.

By following these steps, you can enhance your SQL Server capabilities when dealing with complex JSON structures. Happy querying!