SQL Server transaction and SELECT statement

Question

I often saw many people use SELECT statement within a transaction. I often use insert/update/delete only in transaction. I just do not understand t

Answer 1

try doing this and you will understand:

Open a two new queries on SSMS (lets call it A and B from now one) and on A, create a simple table like this:

create table transTest(id int)
insert into transTest values(1)

now, do the following:

do select * from transTest in both of them. You will see the value 1

On A run:

set transaction isolation level read committed

On B run:

begin transaction
insert into transTest values(2)

On A run:

select * from transTest

you will see that the query wont finish because it is locked by the transaction on A

On B run:

commit transaction

Go back to A and you will see that the query finished

Repeat the test with set transaction isolation level read uncommitted on A you will see that the query wont be locked by the transaction