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DBMS Interview Questions

What is normalization? What are different types of normalization

There is set of rules that have been established to aid in the design of tables that are meant to be connected through relationships. This set of rules is known as Normalization. Benefits of normalizing your database include: Avoiding repetitive entries Reducing required storage space Preventing the need to restructure existing tables to accommodate new …

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What is Data Mining

Data mining is a concept by which we can analyze the current data from different perspectives and summarize the information in more useful manner. It’s mostly used either to derive some valuable information from the existing data or to predict sales to increase customer market. There are two basic aims of Data mining:- Prediction: – …

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What is a database?

A Database is a logical, consistent and organized collection of data that it can easily be accessed, managed and updated. Databases, also known as electronic databases are structured to provide the facility of creation, insertion, updating of the data efficiently and are stored in the form of a file or set of files, on the …

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What are the three levels of data abstraction?

Following are three levels of data abstraction: Physical level: It is the lowest level of abstraction. It describes how data are stored. Logical level: It is the next higher level of abstraction. It describes what data are stored in the database and what the relationship among those data is. View level: It is the highest …

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What are the integrity rules in DBMS?

Data integrity is one significant aspect while maintaining the database. So, data integrity is enforced in the database system by imposing a series of rules. Those set of integrity is known as the integrity rules. There are two integrity rules in DBMS: Entity Integrity : It specifies that “Primary key cannot have a NULL value.” …

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What is the difference between a shared lock and exclusive lock?

Shared lock: Shared lock is required for reading a data item. In the shared lock, many transactions may hold a lock on the same data item. When more than one transaction is allowed to read the data items then that is known as the shared lock. Exclusive lock: When any transaction is about to perform …

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What is de-normalization

Denormalization is the process of putting one fact in numerous places (its vice-versa of normalization).Only one valid reason exists for denormalizing a relational design – to enhance performance.The sacrifice to performance is that you increase redundancy in database.

What’s the difference between DELETE and TRUNCATE

Following are difference between them: DELETE TABLE syntax logs the deletes thus making the delete operations low. TRUNCATE table does not log any information but it logs information about deallocation of data page of the table. So TRUNCATE table is faster as compared to delete table. DELETE table can have criteria while TRUNCATE can not. …

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Compare Data mining and Data Warehousing

Data Warehousing” is technical process where we are making our data centralized while “Data mining” is more of business activity which will analyze how good your business is doing or predict how it will do in the future coming times using the current data. As said before “Data Warehousing” is not a need for “Data …

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