A checkpoint is like a snapshot of the DBMS state. Using checkpoints, the DBMS can reduce the amount of work to be done during a restart in the event of subsequent crashes. Checkpoints are used for the recovery of the database after the system crash. Checkpoints are used in the log-based recovery system. When due to a system crash we need to restart the system then at that point we use checkpoints. So that, we don’t have to perform the…
Relational Calculus is a Non-procedural Query Language which uses mathematical predicate calculus instead of algebra. Relational calculus doesn’t work on mathematics fundamentals such as algebra, differential, integration, etc. That’s why it is also known as predicate calculus. There is two type of relational calculus: Tuple relational calculus Domain relational calculus Relational calculus is a theoretical framework within relational database management systems (RDBMS) used to describe queries declaratively. It’s a non-procedural language that focuses on what data to retrieve rather than…
Data independence specifies that “the application is independent of the storage structure and access strategy of data.” It makes you able to modify the schema definition at one level without altering the schema definition in the next higher level. It makes you able to modify the schema definition in one level should not affect the schema definition in the next higher level. There are two types of Data Independence: Physical Data Independence: Physical data is the data stored in the…
If you are looking for Corporate Assessment Test for Interview Screening the Candidates who applied for job vacancies, you are at right place. We are offering Corporate Assessment Test for Interview Screening. Contact us in chat box, we will call you back.
ORDER BY clause helps to sort the data in either ascending order to descending order. Ascending order sort query: SELECT name,age FROM pcdsEmployee ORDER BY age ASC Descending order sort query SELECT name FROM pcdsEmployee ORDER BY age DESC The correct answer for “What is the ORDER BY clause in a database management system (DBMS)?” would be: “The ORDER BY clause is used in SQL (Structured Query Language) to sort the result set of a query in ascending or descending…
The transparent DBMS is a type of DBMS which keeps its physical structure hidden from users. Physical structure or physical storage structure implies to the memory manager of the DBMS, and it describes how the data stored on disk. A transparent DBMS (Database Management System) is one that provides a seamless interface to users and applications, hiding the complexities of data storage, retrieval, and management. In other words, users interact with the database system as if it were a single…
The term query optimization specifies an efficient execution plan for evaluating a query that has the least estimated cost. The concept of query optimization came into the frame when there were a number of methods, and algorithms existed for the same task then the question arose that which one is more efficient and the process of determining the efficient way is known as query optimization. There are many benefits of query optimization: It reduces the time and space complexity. More…
he Join operation is one of the most useful activities in relational algebra. It is most commonly used way to combine information from two or more relations. A Join is always performed on the basis of the same or related column. Most complex queries of SQL involve JOIN command. There are following types of join: Inner joins: Inner join is of 3 categories. They are: Theta join Natural join Equi join Outer joins: Outer join have three types. They are:…
If you are looking for Self Assessment Technical Mock Test to prepare you Interview, you are at right place. We are offering Self Assessment Technical Interview Mock Test Series. Contact us in chat box, we will call you back.
INNER JOIN Inner join shows matches only when they exist in both tables. Example in the below SQL there are two tables Customers and Orders and the inner join in made on Customers.Customerid and Orders.Customerid. So this SQL will only give you result with customers who have orders. If the customer does not have order it will not display that record. SELECT Customers.*, Orders.* FROM Customers INNER JOIN Orders ON Customers.CustomerID =Orders.CustomerID LEFT OUTER JOIN Left join will display all…