THROW Statement for SQL2012

THROW Statement

THROW statement raises an exception and transfers execution to a CATCH block of a TRY…CATCH construct in SQL Server 2012.

Syntax:

THROW [ { error_number | @local_variable },
        { message | @local_variable },
    { state | @local_variable }
] [ ; ]

 The statement before the THROW statement must be followed by the semicolon (;) statement terminator. 

 If a TRY…CATCH construct is not available, the session is ended. The line number and procedure where the exception is raised are set. The severity is set to 16.

 If the THROW statement is specified withoutü parameters, it must appear inside a CATCH block. This causes the caught exception to be raised. Any error that occurs in a THROW statement causes the statement batch to be ended.

Differences Between RAISERROR and THROW

Examples:
USE tempdb;
GO
CREATE TABLE dbo.TestRethrow
(    ID INT PRIMARY KEY
);
BEGIN TRY
    INSERT dbo.TestRethrow(ID) VALUES(1);
--  Force error 2627, Violation of PRIMARY KEY constraint to be raised.
    INSERT dbo.TestRethrow(ID) VALUES(1);
END TRY
BEGIN CATCH
    PRINT 'In catch block.';
    THROW;
END CATCH;

PRINT 'In catch block.';
Msg 2627, Level 14, State 1, Line 1
Violation of PRIMARY KEY constraint 'PK__TestReth__3214EC272E3BD7D3'. Cannot insert duplicate key in object 'dbo.TestRethrow'.
The statement has been terminated.