SQL Server STRING_ESCAPE Function


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The STRING_ESCAPE returns special characters that are escaped so they can be part of the string. The function is valid in SQL Server 2016 and later.

Syntax

STRING_ESCAPE(expression,rules)

Parameters

  • expression - this is a string of character with special characters to escape.
  • rules – the rules applied to the expression, currently the only value supported is 'json'.

The following characters can be escaped:

Character Escaped Value
" \"
\ \\
/ \/
Backspace \b
Form feed \f
New line /n
Carriage return \r
Horizontal tab \t

Simple STRING_ESCAPE Example

The following example shows how to escape a message with special characters.

 SELECT STRING_ESCAPE('/hello everybody  
 How are you \','json') as msg

The following characters are escaped:

  • forward slash
  • carriage return
  • new line
  • backslash
simple STRING_ESCAPE function example

Example with JSON data

The following uses a variable with JSON data and special characters.

declare @jsonvar VARCHAR(max)=
'[
  {
    "firstname": "Sarah",
    "lastname": "Connor",
    "skills": ["guns\", "fight   "]
  },
  {
    "firstname": "John",
    "lastname": "Connor"
    "skills": ["hacking
         \/"]
  }
]'

If we select the variable, we will see the values escaped.

SELECT STRING_ESCAPE(@jsonvar,'json')
show JSON variable escaped

Show Special Characters Escaped

The following example will show some characters and the escaped values.

WITH sequence(count) AS
(
 SELECT 0
 UNION ALL
 SELECT count+1 FROM sequence WHERE count < 17
)
SELECT CONCAT('CHAR(',count,')') controlchar,STRING_ESCAPE(char([count]),'JSON') escapedcharacters FROM sequence;
List of special characters escaped

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Last Update: 11/29/2021




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