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Commit d76ee0a

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Added try/catch.
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‎docs/findings/SQLCodeDevelopment.md

Lines changed: 131 additions & 85 deletions
Original file line numberDiff line numberDiff line change
@@ -150,50 +150,71 @@ Consider using [sp_CRUDGen](https://github.com/kevinmartintech/sp_CRUDGen) to ge
150150
```sql
151151
SET NOCOUNT, XACT_ABORT ON;
152152

153-
BEGIN TRANSACTION;
153+
BEGIN TRY
154+
BEGIN TRANSACTION;
154155

155-
UPDATE
156-
dbo.Person WITH (UPDLOCK, SERIALIZABLE)
157-
SET
158-
FirstName = 'Kevin'
159-
WHERE
160-
LastName = 'Martin';
156+
UPDATE
157+
dbo.Person WITH (UPDLOCK, SERIALIZABLE)
158+
SET
159+
FirstName = 'Kevin'
160+
WHERE LastName = 'Martin';
161161

162-
IF @@ROWCOUNT = 0
162+
IF @@ROWCOUNT = 0
163163
BEGIN
164164
INSERT dbo.Person (FirstName, LastName) VALUES ('Kevin', 'Martin');
165165
END;
166166

167-
COMMIT TRANSACTION;
167+
COMMIT TRANSACTION;
168+
END TRY
169+
BEGIN CATCH
170+
IF @@TRANCOUNT > 0
171+
BEGIN
172+
ROLLBACK TRANSACTION;
173+
END;
174+
175+
THROW;
176+
END CATCH;
168177
```
169178

170179
**Use this UPSERT pattern when a record insert is more likely:** Don't worry about checking for a records existence just perform the insert.
171180

172181
```sql
173182
SET NOCOUNT, XACT_ABORT ON;
174183

175-
BEGIN TRANSACTION;
184+
BEGIN TRY
185+
BEGIN TRANSACTION;
176186

177-
INSERT dbo.Person (FirstName, LastName)
178-
SELECT
179-
'Kevin'
180-
,'Martin'
181-
WHERE
182-
NOT EXISTS (
187+
INSERT dbo.Person
188+
(
189+
FirstName,
190+
LastName
191+
)
183192
SELECT
184-
1
185-
FROM
186-
dbo.Person WITH (UPDLOCK, SERIALIZABLE)
187-
WHERE
188-
LastName = 'Martin'
189-
);
193+
'Kevin',
194+
'Martin'
195+
WHERE NOT EXISTS
196+
(
197+
SELECT
198+
1
199+
FROM dbo.Person WITH (UPDLOCK, SERIALIZABLE)
200+
WHERE LastName = 'Martin'
201+
);
190202

191-
IF @@ROWCOUNT = 0
203+
IF @@ROWCOUNT = 0
192204
BEGIN
193205
UPDATE dbo.Person SET FirstName = 'Kevin' WHERE LastName = 'Martin';
194206
END;
195207

196-
COMMIT TRANSACTION;
208+
COMMIT TRANSACTION;
209+
END TRY
210+
BEGIN CATCH
211+
IF @@TRANCOUNT > 0
212+
BEGIN
213+
ROLLBACK TRANSACTION;
214+
END;
215+
216+
THROW;
217+
END CATCH;
197218
```
198219

199220
**Use this UPSERT pattern to allow the client application to handle the exception:** Ensure you handle the exception in your code.
@@ -220,61 +241,77 @@ For JSON, XML or comma-separated list ensure you insert the records into a tempo
220241
```sql
221242
SET NOCOUNT, XACT_ABORT ON;
222243

223-
BEGIN TRANSACTION;
224-
225-
/***************************************************************
226-
** Create temp table to store the updates
227-
****************************************************************/
228-
CREATE TABLE #Update (
229-
FirstName varchar(50) NOT NULL
230-
,LastName varchar(50) NOT NULL
231-
);
232-
233-
INSERT INTO #Update (FirstName, LastName)
234-
VALUES ('Kevin', 'Martin')
235-
,('Jean-Luc', 'Picard');
236-
237-
238-
/***************************************************************
239-
** Perform Updates (WHEN MATCHED)
240-
****************************************************************/
241-
UPDATE
242-
P WITH (UPDLOCK, SERIALIZABLE)
243-
SET
244-
P.FirstName = U.FirstName
245-
FROM
246-
dbo.Person AS P
247-
INNER JOIN #Update AS U ON P.LastName = U.LastName;
248-
249-
250-
/***************************************************************
251-
** Perform Inserts (WHEN NOT MATCHED [BY TARGET])
252-
****************************************************************/
253-
INSERT dbo.Person (FirstName, LastName)
254-
SELECT
255-
U.FirstName
256-
,U.LastName
257-
FROM
258-
#Update AS U
259-
WHERE
260-
NOT EXISTS (
261-
SELECT * FROM dbo.Person AS P WHERE P.LastName = U.LastName
262-
);
263-
244+
BEGIN TRY
245+
BEGIN TRANSACTION;
264246

265-
/***************************************************************
266-
** Perform Deletes (WHEN NOT MATCHED BY SOURCE)
267-
****************************************************************/
268-
DELETE
269-
P
270-
FROM
271-
dbo.Person AS P
272-
LEFT OUTER JOIN #Update AS U ON P.LastName = U.LastName
273-
WHERE
274-
U.LastName IS NULL;
247+
/***************************************************************
248+
** Create temp table to store the updates
249+
****************************************************************/
250+
CREATE TABLE #Update
251+
(
252+
FirstName varchar(50) NOT NULL,
253+
LastName varchar(50) NOT NULL
254+
);
255+
256+
INSERT INTO #Update
257+
(
258+
FirstName,
259+
LastName
260+
)
261+
VALUES
262+
('Kevin', 'Martin'),
263+
('Jean-Luc', 'Picard');
264+
265+
266+
/***************************************************************
267+
** Perform Updates (WHEN MATCHED)
268+
****************************************************************/
269+
UPDATE
270+
P WITH (UPDLOCK, SERIALIZABLE)
271+
SET
272+
P.FirstName = U.FirstName
273+
FROM dbo.Person AS P
274+
INNER JOIN #Update AS U
275+
ON P.LastName = U.LastName;
276+
277+
278+
/***************************************************************
279+
** Perform Inserts (WHEN NOT MATCHED [BY TARGET])
280+
****************************************************************/
281+
INSERT dbo.Person
282+
(
283+
FirstName,
284+
LastName
285+
)
286+
SELECT
287+
U.FirstName,
288+
U.LastName
289+
FROM #Update AS U
290+
WHERE NOT EXISTS
291+
(
292+
SELECT * FROM dbo.Person AS P WHERE P.LastName = U.LastName
293+
);
294+
295+
296+
/***************************************************************
297+
** Perform Deletes (WHEN NOT MATCHED BY SOURCE)
298+
****************************************************************/
299+
DELETE P
300+
FROM dbo.Person AS P
301+
LEFT OUTER JOIN #Update AS U
302+
ON P.LastName = U.LastName
303+
WHERE U.LastName IS NULL;
275304

305+
COMMIT TRANSACTION;
306+
END TRY
307+
BEGIN CATCH
308+
IF @@TRANCOUNT > 0
309+
BEGIN
310+
ROLLBACK TRANSACTION;
311+
END;
276312

277-
COMMIT TRANSACTION;
313+
THROW;
314+
END CATCH;
278315
```
279316

280317
**Do not use this UPSERT pattern:** It will produce primary key violations when run concurrently.
@@ -331,19 +368,28 @@ WHEN NOT MATCHED BY SOURCE THEN
331368
This method will not prevent a race condition and the last update will win.
332369

333370
```sql
334-
SET NOCOUNT, XACT_ABORT ON;
335-
BEGIN TRANSACTION;
371+
BEGIN TRY
372+
BEGIN TRANSACTION;
336373

337-
IF EXISTS (SELECT * FROM dbo.Person WITH (UPDLOCK, SERIALIZABLE) WHERE PersonId = @PersonId)
338-
BEGIN
339-
UPDATE dbo.Person SET FirstName = @FirstName WHERE PersonId = @PersonId;
340-
END;
341-
ELSE
374+
IF EXISTS (SELECT * FROM dbo.Person WITH (UPDLOCK, SERIALIZABLE) WHERE PersonId = @PersonId)
375+
BEGIN
376+
UPDATE dbo.Person SET FirstName = @FirstName WHERE PersonId = @PersonId;
377+
END;
378+
ELSE
379+
BEGIN
380+
INSERT dbo.Person (PersonId, FirstName) VALUES (@PersonId, @FirstName);
381+
END;
382+
383+
COMMIT TRANSACTION;
384+
END TRY
385+
BEGIN CATCH
386+
IF @@TRANCOUNT > 0
342387
BEGIN
343-
INSERT dbo.Person (PersonId, FirstName) VALUES (@PersonId, @FirstName);
388+
ROLLBACK TRANSACTION;
344389
END;
345390

346-
COMMIT TRANSACTION;
391+
THROW;
392+
END CATCH;
347393
```
348394

349395
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