Using TRY / CATCH to perform INSERT / UPDATE - sql-server

Question

I have this pattern in a number of stored procedures
-- Table1
[id] [int] IDENTITY(1,1) NOT NULL
[data] [varchar](512) NULL
[count] INT NULL
-- 'data' is unique, with a unique index on 'data' in 'Table1'
BEGIN TRY
INSERT INTO Table1 (data, count) SELECT #data,1;
END TRY
BEGIN CATCH
UPDATE Table1 SET count = count + 1 WHERE data = #data;
END CATCH
I've been slammed before for using this pattern
You should never have exception "catching" in your normal logic flow. (Thus why it is called an "exception"..it should be exceptional (rare). Put a exists check around your INSERT. "if not exists (select null from Data where data = #data) begin /* insert here */ END
However, I can't see a way around it in this instance. Consider the following alternative approaches.
INSERT INTO Table1 (data,count)
SELECT #data,1 WHERE NOT EXISTS
(SELECT 1 FROM Table1 WHERE data = #data)
If I do this, it means every insert is unique, but I can't 'catch' an update condition.
DECLARE #id INT;
SET #id = (SELECT id FROM Table1 WHERE data = #data)
IF(#id IS NULL)
INSERT INTO Table1 (data, count) SELECT #data,1;
ELSE
UPDATE Table1 SET count = count + 1 WHERE data = #data;
If I do this, I have a race condition between the check and the insert, so I could have duplicates inserted.
BEGIN TRANSACTION
DECLARE #id INT;
SET #id = (SELECT id FROM Table1 WHERE data = #data)
IF(#id IS NULL)
INSERT INTO Table1 (data, count) SELECT #data,1;
ELSE
UPDATE Table1 SET count = count + 1 WHERE data = #data;
END TRANSACTION
If I wrap this in a TRANSACTION it adds more overhead. I know TRY/CATCH also brings overhead but I think TRANSACTION adds more - anyone know?.
People keep telling me that using TRY/CATCH in normal app logic is BAD, but won't tell me why
Note: I'm running SQL Server 2005 on at least one box, so I can't use MERGE

Answer 1

Try to update and if it's failed - to insert new.
BEGIN TRANSACTION
UPDATE t
SET
t.count = t.count + 1
FROM Table1 t
WHERE t.data = #data
IF (##ROWCOUNT = 0)
BEGIN
INSERT INTO Table1
(data, count)
VALUES
(#data, 1)
END
COMMIT TRANSACTION

Answer 2

The explicit transaction is the cost of doing business with a conditional INSERT/UPDATE in order to address concurrency. The example below uses locking hints to a avoid race condition with this code.
BEGIN TRANSACTION;
INSERT INTO Table1
( data
, count
)
SELECT #data
, 1
WHERE NOT EXISTS ( SELECT 1
FROM Table1 WITH ( UPDLOCK, HOLDLOCK )
WHERE data = #data );
IF ##ROWCOUNT = 0
UPDATE Table1
SET count = count + 1
WHERE data = #data;
COMMIT;
If the more common path is the UPDATE, try that first followed by the conditional INSERT.