SQL Tutorial - How to Read Data from XML Column? XQuery Methods · · Admin

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In this SQL tutorial, we will learn how to read data from a XML column using SQL Query. We will explore two methods - value() ...

SQL Tutorial: Reading Data from an XML Column Using XQuery Methods

In SQL Server, you can store XML data in a column of the XML data type. This tutorial will guide you through reading data from an XML column using various XQuery methods.

Step 1: Setting Up the Environment

First, create a table that includes an XML column:

sql

CREATE TABLE Products (
    ProductID INT PRIMARY KEY,
    ProductInfo XML
);

Step 2: Inserting XML Data

Insert some sample XML data into the ProductInfo column:

sql

INSERT INTO Products (ProductID, ProductInfo)
VALUES 
(1, '<product><name>Apple</name><price>1.20</price><category>Fruit</category></product>'),
(2, '<product><name>Banana</name><price>0.50</price><category>Fruit</category></product>'),
(3, '<product><name>Carrot</name><price>0.70</price><category>Vegetable</category></product>');

Step 3: Querying XML Data

You can use various XQuery methods to extract data from the XML column.

Example 1: Extracting Product Names

To retrieve all product names, use the .value() method:

sql

SELECT 
    ProductID,
    ProductInfo.value('(/product/name)[1]', 'VARCHAR(50)') AS ProductName
FROM Products;

Example 2: Extracting Prices

To get the prices of all products, you can also use the .value() method:

sql

SELECT 
    ProductID,
    ProductInfo.value('(/product/price)[1]', 'DECIMAL(10,2)') AS Price
FROM Products;

Example 3: Extracting Multiple Attributes

If you want to extract multiple attributes (e.g., name, price, and category), you can use the CROSS APPLY method to shred the XML:

sql

SELECT 
    p.ProductID,
    prod.value('(name)[1]', 'VARCHAR(50)') AS ProductName,
    prod.value('(price)[1]', 'DECIMAL(10,2)') AS Price,
    prod.value('(category)[1]', 'VARCHAR(50)') AS Category
FROM Products p
CROSS APPLY ProductInfo.nodes('/product') AS prod(prod);

Step 4: Filtering Data

You can filter the XML data based on specific conditions. For instance, to find all products in the "Fruit" category:

sql

SELECT 
    p.ProductID,
    prod.value('(name)[1]', 'VARCHAR(50)') AS ProductName,
    prod.value('(price)[1]', 'DECIMAL(10,2)') AS Price
FROM Products p
CROSS APPLY ProductInfo.nodes('/product') AS prod(prod)
WHERE prod.value('(category)[1]', 'VARCHAR(50)') = 'Fruit';

Conclusion

Using XQuery methods in SQL Server allows you to efficiently read and manipulate XML data stored in XML columns. With methods like .value() and CROSS APPLY, you can extract specific information, filter data, and work with complex XML structures. Experiment with these techniques to enhance your data querying capabilities!

SQL Tutorial - How to Read Data from XML Column? XQuery Methods

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