Ado.net Series quiz about Transaction isolation levels

The proposed problem of ADO:

Some people, in order to avoid transactional concurrency problems, set the isolation level of the transaction to the highest level serilizable, resulting in unexpected problems.

Suppose there is a table T1
There is only one field field2 varchar (20) type.

He executed a code in the code:

Set TRANSACTION ISOLATION level serializable
BEGIN Tran
SELECT * FROM t1
WAITFOR DELAY ' 00:00:30 '
INSERT into T1 values (' 123 ')
If @ @error =0
Commit Tran
Else
Rollback Tran

Problem:
1. Do not rush to execute this code, like this code more than a person to execute at the same time what is the problem
2. He violated those principles of database transaction design.


Once you've solved it, you'll find that it's not used properly, it's easy to have problems, even serious consequences.