ISJSON Function in Sql Server 2016

ISJSON function validates whether the string parameter supplied to it is a valid JSON or not. If supplied string is a valid JSON then it will return value as 1, otherwise it returns the value 0. In case input is a NULL then it returns output as NULL.

Syntax:

ISJSON( String_Expression )

WHERE String_Expression can be a table column or a string (i.e. Varchar/NVarchar) variable or a string constant. And this string expression is evaluated to check whether it is a valid JSON.

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Let us understand this function with extensive list of examples:

Example 1: Input is a valid JSON, in this case the ISJSON function will return value as 1

DECLARE @JSONText NVarchar(Max) = '[{"Id":1,"Name":"Basavaraj"},
			             {"Id":2,"Name":"Kalpana"}]'
IF ISJSON ( @JSONText ) = 1
	PRINT 'Valid JSON'

RESULT:
ISJSON Valid JSON

Example 2: Input is an InValid JSON, in this case the ISJSON function will return value as 0

DECLARE @JSONText NVarchar(Max) = 'Basavaraj'
IF ISJSON ( @JSONText ) = 0
	PRINT 'InValid JSON'

RESULT:
ISJSON InValid JSON

Example 3: Input is a NULL value, in this case the ISJSON function will return value as 0

SELECT ISJSON ( NULL ) 'ISJSON RESULT'

RESULT:
ISJSON NULL OutPut
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