Category Archives: DBMS

SQL | Arithmetic Operators

Prerequisite: Basic Select statement, Insert into clause, Sql Create Clause, SQL Aliases We can use various Arithmetic Operators on the data stored in the tables.… Read More »

SQL | MERGE Statement


Prerequisite – INSERT, UPDATE, DELETE The MERGE command in SQL is actually a combination of three SQL statements: INSERT, UPDATE and DELETE. In simple words,… Read More »

DBMS | Multimedia Database

Multimedia database is the collection of interrelated multimedia data that includes text, graphics (sketches, drawings), images, animations, video, audio etc and have vast amounts of… Read More »

DBMS | Enhanced ER Model

Prerequisite – Introduction of ER Model Enhanced entity-relationship diagrams are advanced database diagrams very similar to regular ER diagrams which represents requirements and complexities of… Read More »

Canonical Cover


Whenever a user updates the database, the system must check whether any of the functional dependencies are getting violated in this process. If there is… Read More »



RAID, or “Redundant Arrays of Inexpensive Disks” is a technique which makes use of a combination of multiple disks instead of using a single disk… Read More »

Query Optimization


Query: A query is a request for information from a database. Query Plans: A query plan (or query execution plan) is an ordered set of… Read More »



ALL & ANY are logical operators in SQL. They return boolean value as a result. ALL ALL operator is used to select all tuples of… Read More »



SQL supports a special value known as NULL which is used to represent the values of attributes that may be unknown or not apply to… Read More »