How FOR JSON escapes special characters and control characters (SQL Server)
Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics (serverless SQL pool only)
This article describes how the FOR JSON
clause of a SQL Server SELECT
statement escapes special characters and represents control characters in the JSON output.
Important
This article describes the built-in support for JSON in Microsoft SQL Server. For general information about escaping and encoding in JSON, see Section 2.5 of the JSON RFC.
If the source data contains special characters, the FOR JSON
clause escapes them in the JSON output with \
, as shown in the following table. This escaping occurs both in the names of properties and in their values.
Special character | Escaped output |
---|---|
Quotation mark (" ) |
\" |
Backslash (\ ) |
\\ |
Slash (/ ) |
\/ |
Backspace | \b |
Form feed | \f |
New line | \n |
Carriage return | \r |
Horizontal tab | \t |
If the source data contains control characters, the FOR JSON
clause encodes them in the JSON output in \u<code>
format, as shown in the following table.
Control character | Encoded output |
---|---|
CHAR(0) | \u0000 |
CHAR(1) | \u0001 |
... | ... |
CHAR(31) | \u001f |
Here's an example of the FOR JSON
output for source data that includes both special characters and control characters.
Query:
SELECT 'VALUE\ /
"' AS [KEY\/"],
CHAR(0) AS '0',
CHAR(1) AS '1',
CHAR(31) AS '31'
FOR JSON PATH;
Result:
[
{
"KEY\\\/\"": "VALUE\\ \/\r\n \"",
"0": "\u0000",
"1": "\u0001",
"31": "\u001f"
}
]