DBMS

Concurrency control is the procedure in DBMS for managing simultaneous operations without conflicting with each another. Concurrent access is quite easy if all users are … Read more

What is Cursor ? Cursor is a pointer in memory area called context area. What is context area ? Context area is a memory area … Read more

What is Trigger ? A trigger is defined as an action taken by database when some database related events occur. Triggers are implicitly fired by … Read more

Five Important aggregate functions are SUM, AVG, MIN, MAX and COUNT. They are called aggregate functions because they summarize the results of a query, rather … Read more

A SQL Join statement is used to combine data or rows from two or more tables based on a common field between them. Different types … Read more

A DBMS based on relational model is called relational database management system or RDBMS.RDBMS uses relational structures to store data. A relation is also called … Read more

OODBMS RDBMS Stores data and methods Stores only data Main objective data encapsulation and data independence Main objective data independence Classes can be reorganized without … Read more

What is Serializability ? Serializability is the concurrency scheme.  Serializability ensures that a schedule for executing concurrent transactions is equivalent to one that executes the … Read more

What are Schedules ? Schedules are sequences that indicate the chronological order in which instructions of concurrent transactions are executed.A schedule must preserve the order … Read more

A transaction is a unit of program execution that accesses and  possibly updates one or more data items in  the database. For example, Money transfer … Read more