Sql-server – SQL Server 2008 Transaction, rollback required

rollbacksql servertransactionstsql

I have a stored procedure that has a BEGIN TRANSACTION and COMMIT TRANSACTION statement. Within the transaction is a select query WITH(XLOCK, ROWLOCK).

The transaction can potentially fail due to some calculations that cause an arithmetic overflow error if out of bounds values are supplied. This error would happen before any insert/update statements.

My question is, should I wrap the transaction in a TRY/CATCH and rollback or is this not really required and all locks would be released automatically if the transaction fails? My only concern here is that SQL would not release all locks of the transaction in case the transaction fails.

Thanks,

Tom

Best Answer

A much easier way is:

set xact_abort on

This will cause the transaction to be rolled back automatically when an error occurs.

Example code:

set xact_abort on
begin transaction
select 1/0
go
print @@trancount -- Prints 0

set xact_abort off
begin transaction
select 1/0
go
print @@trancount -- Prints 1

If you execute the second segment multiple times, you'll see the transaction count increase to 2,3,4 etc. A single run of the first segment resets all transactions.

Syntax:

ALTER TABLE {TABLENAME} 
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES

Example:

ALTER TABLE SomeTable
        ADD SomeCol Bit NULL --Or NOT NULL.
 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
    DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.

Notes:

Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6

Optional With-Values Statement:
The WITH VALUES is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES or not.

How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable and do not Specify SomeCol's value, then it will Default to 0.
If you insert a Record and Specify SomeCol's value as NULL (and your column allows nulls),
then the Default-Constraint will not be used and NULL will be inserted as the Value.

Notes were based on everyone's great feedback below.
Special Thanks to:
@Yatrix, @WalterStabosz, @YahooSerious, and @StackMan for their Comments.

Sql – How to return only the Date from a SQL Server DateTime datatype

SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, @your_date))

for example

SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE()))

gives me

2008-09-22 00:00:00.000

Pros:

No varchar<->datetime conversions required
No need to think about locale

Best Answer

Related Solutions

Sql – Add a column with a default value to an existing table in SQL Server

Syntax:

Example:

Notes:

Sql – How to return only the Date from a SQL Server DateTime datatype

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