How to Output a Nested JSON Array into a SQL Table

Learn how to efficiently select a nested JSON array and output it into a structured SQL table format in SQL Server.
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How to Output a Nested JSON Array into a SQL Table

JSON (JavaScript Object Notation) is a popular data format for storing and sharing data, especially in web applications. When you're working with SQL Server, you might encounter a common scenario: how to output a nested JSON array into a structured table format. In this guide, we'll tackle this issue by breaking down how to select a JSON array and convert it into a table.

Problem Breakdown

Suppose you have a JSON structure representing orders, each containing a nested line_items array. Your goal is to loop through the orders array and capture the line_item IDs. Here’s a sample JSON snippet you're working with:

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Given the sample JSON above, you want to produce the following output in a table format:

id12Solution Overview

To achieve the desired output, we will make use of SQL Server's JSON functions. The primary function we will leverage is OPENJSON, which allows us to parse JSON text into rows. Specifically, we'll employ a CROSS APPLY to facilitate the retrieval of nested arrays.

Detailed Solution Steps

Declare Your JSON Variable: First, declare a variable to hold your JSON data. For this example, we will use the JSON provided above.

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Use OPENJSON and CROSS APPLY: Next, we will write a SQL query that will use the OPENJSON function along with CROSS APPLY to extract the IDs from the line_items array. Here's how the query looks:

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The first OPENJSON command reads the orders array.

CROSS APPLY is used to handle the nested line_items array, allowing us to operate on each item in that array.

Running the Query: When you execute the above query, you should see the following output:

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

Conclusion

By using SQL Server's JSON functions, such as OPENJSON and CROSS APPLY, we can effectively extract and display data from nested JSON arrays in a structured table format. This method is straightforward and can be adapted to suit a variety of JSON structures that you may encounter in your work.

Now that you know how to convert a JSON array into a table format, you can apply this knowledge to your own projects and queries. Happy coding!