XML XPath Comparison Operators

• XPath provides comparison operators that allow us to compare two values for the purpose of evaluating conditions.
• These operators are used in XPath expressions to filter and select nodes from an XML document.

Syntax

The following comparison operators are supported in XPath:

Operator	Description
=	Equal to
!=	Not equal to
<	Less than
>	Greater than
<=	Less than or equal to
>=	Greater than or equal to

The syntax for using a comparison operator in an XPath expression is as follows:

expression1 operator expression2

Where expression1 and expression2 are the expressions being compared, and operator is one of the comparison operators listed in the table above.

Example

Consider the following XML document:

<bookstore>
  <book>
    <title>XPath and XQuery</title>
    <author>Priscilla Walmsley</author>
    <price>30.00</price>
  </book>
  <book>
    <title>XML Schema</title>
    <author>Eric van der Vlist</author>
    <price>20.00</price>
  </book>
  <book>
    <title>XSLT</title>
    <author>Michael Kay</author>
    <price>40.00</price>
  </book>
</bookstore>

To select all the books that have a price greater than or equal to 30.00, we can use the following XPath expression:

/bookstore/book[price >= 30.00]

The expression price >= 30.00 compares the price element of each book element with the value 30.00.

Output

The output of the above XPath expression would be:

<book>
  <title>XPath and XQuery</title>
  <author>Priscilla Walmsley</author>
  <price>30.00</price>
</book>
<book>
  <title>XSLT</title>
  <author>Michael Kay</author>
  <price>40.00</price>
</book>

This is because only the first and the third book elements have a price element with a value greater than or equal to 30.00.

Explanation

The comparison operator >= in the XPath expression /bookstore/book[price >= 30.00] works by comparing the price element of each book element with the value 30.00. If the value of the price element is greater than or equal to 30.00, the corresponding book element is selected.

Use

Comparison operators are commonly used in XPath expressions to filter and select nodes from an XML document based on a specific condition. For example, we can use comparison operators to:

• Select all the book elements that have a price element with a value greater than or equal to a specific amount.
• Select all the employee elements that have a salary element with a value less than a specific amount.
• Select all the student elements that have a grade element with a value greater than or equal to a specific grade.

Important Points

• Comparison operators are used in XPath expressions to evaluate conditions.
• XPath supports six comparison operators: =, !=, <, >, <=, and >=.
• Comparison operators can be used to filter and select nodes from an XML document based on specific conditions.
• Comparison operators can be combined with logical operators (such as and, or, and not) to create more complex conditions.

Summary

XPath comparison operators allow us to compare values and evaluate conditions in XPath expressions. These operators are used to filter and select nodes from an XML document based on specific conditions. XPath supports six comparison operators: =, !=, <, >, <=, and >=. Comparison operators can be used in combination with other XPath features, such as axes and logical operators, to create more complex expressions.