Lock (database)

Imagine you have a toy box with lots of toys inside. You and your friend both want to play with the same toy at the same time. What should you do?

One idea is to take turns so that each of you gets a chance to play with it. But what if one of you wants to play for a really long time? That wouldn't be very fair to the other person.

Another idea is to put a lock on the toy box that only one person can open at a time. This way, if you want to play with the toy, you can open the box and your friend will have to wait until you're done. Once you put the toy back in the box and lock it, your friend can then open it and play with the toy.

In a database, there are lots of different people who want to change or access information at the same time. This is called concurrency. Just like with the toy box, we need a way to make sure that only one person can make changes to the information at a time.

That's where locks come in. A lock is like a virtual key that prevents other people from making changes to the same piece of information that you're working on. Just like how you can only open the toy box with the key, only one person can hold the lock for a particular piece of information at a time.

This helps prevent errors and conflicts that might occur if multiple people were able to change or access the same data at the same time. So just like with the toy box, the lock ensures that everyone gets a fair chance to access and use the data without interfering with each other.