The STRING_ESCAPE function in SQL Server is used to escape special characters in a string to make it safe for use in formats like JSON or XML. This function helps to prevent issues like SQL injection when dealing with user input or dynamically generated content.
Here’s how to use STRING_ESCAPE:
Syntax
STRING_ESCAPE ( string_value , escape_type )
- string_value: The string you want to escape.
- escape_type: The type of escaping to be applied. As of the latest versions, valid values are 'json' and 'xml'.
Example Usage
Escaping JSON
To escape special characters in a JSON string, you can do the following:
DECLARE @jsonString NVARCHAR(MAX) = '{"name": "John Doe", "message": "Hello "world"!"}';
SELECT STRING_ESCAPE(@jsonString, 'json') AS EscapedJson;
In this example, the STRING_ESCAPE function is used to escape quotes and other special characters that can cause issues in a JSON context.
Escaping XML
To escape special characters in an XML string, you would use:
DECLARE @xmlString NVARCHAR(MAX) = '<note><to>Tove</to><from>Jani</from><body>Don''t forget me this weekend!</body></note>';
SELECT STRING_ESCAPE(@xmlString, 'xml') AS EscapedXml;
This would escape characters like <, >, &, and others as necessary for XML formatting.
Note
- Always ensure you are using the appropriate escape type based on the context in which you are using the string.
- The STRING_ESCAPE function is available in SQL Server 2016 and later.
Using this function enhances data security and integrity, particularly in scenarios involving special characters that must be validated or sanitized before insertion into databases or output in documents.