Currently SQL Server 2016 CTP 3 and later releases support NVARCHAR(max) fields with JSON content. However since the type NVARCHAR(max) is totally free-form, there is no constraint on these fields.

Can I declare a constraint that prevents insertion of a non-null value that is not valid JSON?


1 Answer 1


Add this constraint:

ALTER TABLE [dbo].[Resource] 
   CHECK ( ISJSON( ExtJSON )> 0 ) 

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