Locking and Concurrency - SQL Server 2012 Internals and Troubleshooting - page 157

READ COMMITTED;
--REPEATABLE READ;

BEGIN TRANSACTION;

SELECT TOP 5
FirstName
,MiddleName
,LastName
,Suffix
FROM Person.Person
ORDER BY LastName;

WAITFOR DELAY '00:00:05.000';

SELECT TOP 5
FirstName
,MiddleName
,LastName
,Suffix
FROM Person.Person
ORDER BY LastName;

COMMIT TRANSACTION;

/*SESSION 2*/
USE AdventureWorks2012;

BEGIN TRANSACTION;

UPDATE Person.Person
SET Suffix = 'Junior'
WHERE LastName = 'Abbas'
AND FirstName = 'Syed';

COMMIT TRANSACTION;

/*
UPDATE Person.Person
SET Suffix = NULL
WHERE LastName = 'Abbas'
AND FirstName = 'Syed';
*/

Providing you execute the update in Session 2 in time, your results
will match Figure 6-4. The i rst read from Session 1, Syed Abbas,
had no sufi x; but in the second read he's now Syed Abbas Junior.
The i rst read, therefore, hasn't been repeatable.

FIGURE 6-4