SQL locks and transactions

1. How to lock a row in a table

Execute in connection

SET transaction isolation level Repeatable read

Begin tran

Select * From tablename with (rowlock) Where id = 3

Waitfor delay '00: 00: 05'

Commit tran

If you execute

Update tablename set colname = '10' where id = 3 -- Wait 5 seconds.

Update tablename set colname = '10' where ID <> 3 -- immediate execution

2. Lock a table in the database

Select * from table with (holdlock)

Note: What is the difference between locking a database table?

Select * from table with (holdlock)
Other transactions can read tables, but cannot update or Delete tables.

Select * from table with (tablockx)
Other transactions cannot read, update, or delete tables.