How to stop insert in a transaction in SQL Server? - sql

Question

Create query using BEGIN TRAN statement to insert two rows within BEGIN TRY if transaction count is greater than 1, catch error and rollback the transaction, otherwise print “transaction committed” (this is my teacher question the idea is that it should not insert more than 1 row by using the ##trancount is greater than one the transaction is rolled back)
This is the code that I wrote
BEGIN TRY
BEGIN TRAN;
INSERT INTO [Info].[Country]([name]) VALUES ('Italy');
PRINT ##TRANCOUNT
BEGIN TRAN
INSERT INTO [Info].[Country]([name]) VALUES ('Jorden');
PRINT ##TRANCOUNT
IF ##TRANCOUNT > 1
PRINT 'Rollback the transaction...';
ELSE
PRINT 'transaction succeeded';
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION
END CATCH;
It keeps inserting the two rows even though the trans count is greater than 1
How can I fix this?!!
This is the result

Answer 1

I suppose you're looking for using ##ROWCOUNT instead of ##TRANCOUNT
BEGIN TRY
BEGIN TRAN MyTran;
INSERT INTO Countries(Name) VALUES
('Italy'),
('Jorden');
IF ##ROWCOUNT > 1
ROLLBACK TRAN MyTran;
ELSE
COMMIT TRAN MyTran;
END TRY
BEGIN CATCH
RAISERROR ('Error Message',
16, -- Severity.
1 -- State.
);
ROLLBACK TRAN MyTran;
END CATCH;
If you really want to use nested transactions and use ##TRANCOUNT
BEGIN TRY
BEGIN TRAN MyTran;
INSERT INTO Countries(Name) VALUES ('Italy');
BEGIN TRAN MySecTran;
INSERT INTO Countries(Name) VALUES ('Jorden');
IF ##TRANCOUNT > 1
ROLLBACK TRAN;
ELSE
COMMIT TRAN;
END TRY
BEGIN CATCH
RAISERROR ('Error Message',
16, -- Severity.
1 -- State.
);
ROLLBACK TRAN;
END CATCH;
Here is a db<>fiddle where you can un-comment one of the two and see how it's working.
Update:
i checked it again. it did not insert any row in the table. but it should insert the first one
Then you need to save the tran as
BEGIN TRY
BEGIN TRAN MyTran;
INSERT INTO Countries(Name) VALUES ('Italy');
SAVE TRAN MySaveTran;
BEGIN TRAN MySecTran;
INSERT INTO Countries(Name) VALUES ('Jorden');
IF ##TRANCOUNT > 1
ROLLBACK TRAN MySaveTran;
COMMIT TRAN;
END TRY
BEGIN CATCH
RAISERROR ('Error Message',
16, -- Severity.
1 -- State.
);
ROLLBACK TRAN;
END CATCH;

Answer 2

BEGIN TRY
BEGIN TRAN;
INSERT INTO [Info].[Country]([name]) VALUES ('Italy');
print ##TRANCOUNT
Begin tran
INSERT INTO [Info].[Country]([name]) VALUES ('Jorden');
print ##TRANCOUNT
if ##TRANCOUNT>1
PRINT 'Rollback the transaction...';
else
print 'transaction successes';
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION
END CATCH;
GO
You are not actually doing a rollback, you're just printing 'Rollback the transaction' change to
BEGIN TRY
BEGIN TRAN;
INSERT INTO [Info].[Country]([name]) VALUES ('Italy');
print ##TRANCOUNT
Begin tran
INSERT INTO [Info].[Country]([name]) VALUES ('Jorden');
print ##TRANCOUNT
if ##TRANCOUNT>1
begin
PRINT 'Rollback the transaction...';
ROLLBACK TRANSACTION
end
else
print 'transaction successes';
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION
END CATCH;
GO

Answer 3

besides the other mentioned mistakes. I think your teacher wants you to make proper use of the try catch pattern. For this you need to know that the CATCH block is only executed when an error occurs inside of the try block.
See TRY...CATCH (Transact-SQL)
You can raise an error using the THROW statement
THROW (Transact-SQL)
IF ##ROWCOUNT > 1
THROW 51000, 'row count greater 1.', 1;