Скачать или смотреть How to Use XQuery for Parsing XML in SQL Server

Learn how to effectively parse XML data using `XQuery` in SQL Server with practical examples and tips. A beginner-friendly guide to manipulating XML structures!
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This video is based on the question https://stackoverflow.com/q/62888770/ asked by the user 'Indi_Rain' ( https://stackoverflow.com/u/13722367/ ) and on the answer https://stackoverflow.com/a/62889694/ provided by the user 'AlwaysLearning' ( https://stackoverflow.com/u/390122/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering XQuery for XML Parsing in SQL Server

If you are working with XML data in SQL Server, understanding how to effectively use XQuery can greatly enhance your ability to manipulate and retrieve the information you need. In this post, we’ll explore a specific question many developers face: How to parse a given XML structure using XQuery?

The Problem at Hand

Let’s start with the XML structure in question. Here’s a simple XML representation containing two string values:

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A developer has tried to parse this XML using XQuery syntax in SQL Server, but faced issues with the output when implementing a loop to print each line item. Here’s the relevant code snippet that was causing trouble:

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The issue here is that the PRINT statement is not displaying output as expected. What’s going wrong?

Analyzing the Issue

The main reason for the issue is that the selection mechanism of XQuery is not effectively capturing the text values. Specifically, when trying to store the value in the variable @ LineItem, the col.value('(string/text())[1]', 'VARCHAR(MAX)') call may yield null values because the reference might not be correct.

Solution: Restructuring the Code

To achieve the desired outcome, the SQL code can be slightly modified. Here’s a revised version that correctly displays the string values from the XML:

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Expected Output

Running the updated loop will yield the following results:

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An Alternative Approach: Returning a Result Set

If the goal is not just to print the line items but to retrieve them as a result set instead, consider using the following SQL code:

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Result

This will provide a structured output like this:

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

Conclusion

Parsing XML in SQL Server using XQuery can seem daunting, but with the right strategies, it becomes much more manageable. Whether you're iterating through elements with a loop or retrieving results as a set, understanding how to properly reference and manipulate XML nodes is crucial for effective data management.

By refining your XQuery skills, you’ll be better equipped to handle XML data in your SQL applications. If you have any further questions or additional scenarios you'd like help with, feel free to reach out in the comments!