Locking and concurrency strategy

- [Instructor] When two or more users…access the same tables at the same time,…they're considered concurrent users.…If the operations that they are performing…are simple reads, then SQL Server…can easily accommodate both users simultaneously.…But once one or more users begin updating…and inserting records into a table…that someone else is reading,…things start to get a little bit more complicated.…SQL Server 2016 provides a number of ways…to manage concurrent data access.…Before we take a look at how to design…a concurrency strategy, it's important to better understand…the problems that can arise so that…we know to deal with them.…

Without any concurrency controls in place,…users might experience lost updates,…uncommitted dependencies, or what's known as a dirty read,…inconsistent analysis, or a nonrepeatable read,…phantom reads, or missing and double reads…caused by row updates.…Let's take a look at what each of these issues looks like…and how to mitigate against them.…A lost update occurs when two or more users…