[database]Functions provided by DBMS

Here is a list of non-exhaustive functions provided by DBMS (Database management system) To prevent data lost during system failure, it should provide reliable recovery service. Provide transaction service for user such as read (select), update, delete, commit, insert, rollback. Provide authorisation service such as permission for user to insert (write new data), update (update … Continue reading [database]Functions provided by DBMS


[DATABASE] File base vs database

This post illustrates the need for database approach to manage data. Problems with file base approach Data is stored in file defined by application, hence there is a possibility of potential useful data needed by another application but not aware by the application that requires it. Because the data is stored in file defined by … Continue reading [DATABASE] File base vs database


Atomicity refers to a transaction is either fully completed or not completed at all, there is no partial complete transaction. This also refers to all or none rule. Consistency refers during transaction the integrity constraints are maintained so that the data are consistent before and after transactions. Isolation refers to changes of one transaction are … Continue reading [DATABASE]ACID property of DBMS

[DATABASE]Difference between inner join, right and left outer join

Creating the tables Data from T1 Data from T2 Left outer join In the below example left table is T1 and right table is T2. Left outer join will cause tuples of the left table (T1) to be preserved, the right table (T2) will display values that match the TID of the left, if there … Continue reading [DATABASE]Difference between inner join, right and left outer join