What are the different types of Lock available in SQL?

[Carol.fire]

Hi Friends,

I am learning SQL and it's near to complete. Even though the concept of "Lock" in SQL is not yet cleared for me. I am totally confused how to understand it.

What are the different types of Lock available in SQL? What is the use them?

Your help will be greatly appreciable..

[Reegan]

Hi,

Basically there are two main types of locks in SQL which is as below:

I) Explicit locks:
user provides this type of lock. There are also three kinds of this lock i.e Table level locks and Row level locks

II) Implicit locks:
This type of lock used by SQL system itself while operations like DML is running.

[opaper]

Hi All,

According to my SQL knowledge,three types of Lock available in SQL:

A. Exclusive lock:This type of lock is used during Update, Delete OR Insert operations.

B. Shared lock: This type of lock is used when you don't want enable to modify OR change the data.

C. Update lock: This type of lock is used during modification OR updation.

[MindSpace]

Hi,

When we want to modify the particular object we can use exclusive lock for this. When we want to reserves object for reading only,then we an use shared lock. From this we can avoid modification of the object. We can apply this lock on one or more objects.
We can't apply this lock on the object when this object already has another lock.We can apply promotable locks on the object which already has shared lock.

I hope this will solve your confusion regarding Lock in SQL...