Hidden tasks performed by DBMS when users update and retrieve data.
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Explanation of Solution
A DBMS is of no use to any user if it's not capable of providing some functions. Updation and retrieval are the fundamental job of a DBMS. Thus, a DBMS must provide to its users the ability to perform same. These tasks are solely the responsibility of a DBMS and a user needs not be aware of them.
The general steps followed in almost all operations are in diagram below:
An operation contains instructions given by users and some tasks that are performed at the backend.
The difference usually occurs at step 2 and 3 where more than one sub operations might be needed to complete the task.
An updation operation can be performed by a user in the following way: by adding a new record, changing an existing records or it's deletion. All these consist of some instructions given by user and some task performed by DBMS.
Updation:
1. adding new records:
User enters an item and requests the DBMS to add a new item into database.
Following tasks are performed by DBMS following the request:
- It checks whether the records already exist in Database
- If not, it creates a new record and adds it to the database.
- Informs the user that the operation is complete, and the record is now a part of the database.
2. Changing a record:
User requests the DBMS to change an item from the database.
Following tasks are performed by DBMS following the request:
- It reads the data from database that needs to be changed.
- It displays the current data to user so that new value can be provided for changing.
- It changes the value as soon as new value is provided.
3. Deleting a record:
User requests the DBMS to delete an item from the database.
Following tasks are performed by DBMS following the request:
- It reads the data from database that needs to be deleted.
- It displays the current data to user so that user is able to see what will be deleted.
- It deletes the value as soon as user confirms the deletion action.
Retrieval:
A user is capable of reading a value from database. Following are the steps performed by DBMS to complete the operation:
- It finds and reads the record from database
- It displays the record to user
Thus, an operation consists of both the task done by a user and the tasks performed by a user. The DBMs is fully capable of performing these sub tasks at backend without the user being aware of it.
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Chapter 7 Solutions
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