Capturing multiple error messages from a single statement inside TRY CATCH

Question

I am running a batch of statements on several columns and tables and want to retrieve information on what errors occur.

The statement is a type change (varchar to nv

Answer 1

MikeCov has answered this, but I didn't want to trust the future documentation. The future is now, so I tested this and can confirm that THROW does indeed return all the error messages.

You can reproduce this with the below script. Run each section between the comments one at a time to see the output.

/*Create tables */

CREATE TABLE dbo.test 
(
columna int primary key
)
GO

CREATE TABLE dbo.test2
(
columnb int 
)
GO

/*Create foreign key between these tables*/
ALTER TABLE dbo.test2  WITH CHECK ADD  CONSTRAINT [FK_test_to_test] FOREIGN KEY(columnb)
REFERENCES dbo.test  (columna)
GO
ALTER TABLE dbo.test2 CHECK CONSTRAINT [FK_test_to_test] 
GO

/* TEST 1 - only returns the last error message */
BEGIN TRY
    ALTER TABLE dbo.test 
    ALTER Column columna varchar
END TRY
BEGIN CATCH
    DECLARE  @ERROR_MESSAGE NVARCHAR(2048) = ERROR_MESSAGE()
    RAISERROR (@ERROR_MESSAGE,16,16)
END CATCH       

/* TEST 2 - Returns both messages, YAY */
BEGIN TRY
    ALTER TABLE dbo.test 
    ALTER Column columna varchar
END TRY
BEGIN CATCH
    THROW;
END CATCH       


/* Clean up */
DROP TABLE dbo.test2
DROP TABLE dbo.test