CS619 Viva Exam Preparation Basic Questions Solved by Arslan

CS619-Final Project · Some Basic Questions Collected By · Arslan · During Viva Exam · Jan 14, 2018 · V-U

Updated.

Difference between assignment operator (=) and equality operator (= =)?

Assignment operator and equality operator are different but they are similar in reading. = operator is used to assign value and the other hand = = operator is used to said equal.

Be careful! The operator = (one equal sign) is not the same as the operator = = (two equal signs), the first one is an assignment operator (assigns the value at its right to the variable at its left) and the other one (= =) is the equality operator that compares whether both expressions in the two sides of it are equal to each other. Thus, in the last expression ((b=3) = = a), we first assigned the value 3 to b and then we compared it to a, that also stores the value 3, so the result of the operation is true.

Why we use [ ] Square Bracket in Programing?

Square brackets [ ] are used for arrays, indexers, and attributes.

What is Data Partitioning?

Data Partitioning is the formal process of determining which data subjects, data occurrence groups, and data characteristics are needed at each data site. It is an orderly process for allocating data to data sites that is done within the same common data architecture. Or Data Partitioning is also the process of logically and/or physically partitioning data into segments that are more easily maintained or accessed. Current RDBMS systems provide this kind of distribution functionality. Partitioning of data helps in performance and utility processing.

Tell me the Example Multi Valued Attribute?

A multivalued attribute can have more than one value at a time for an attribute. For ex., skills of a surgeon is a multivalued attribute since a surgeon can have more than one skill.

Database-design

Class Definition:

Class is a collection of data types & function that are use the user defined variables. Or Class is a related collection of methods and variables.

What is DML?

A data manipulation language (DML) is a family of syntax elements similar to a computer programming language used for selecting, inserting, deleting and updating data in a database. Performing read-only queries of data is sometimes also considered a component of DML.

What is normalization? And how many types of normalization? Will number of tables reduce or increase as a result of normalization?

Normalization is the process of organizing data into a related table; it also eliminates redundancy and increases the integrity which improves performance of the query. To normalize a database, we divide the database into tables and establish relationships between the tables

In 1st NF:

An entity is in the first normal form if it contains no repeating groups.

In 2nd NF:

A relation is in 2NF if it is in 1NF and every non-key attribute is fully dependent on each candidate key of the relation.

In 3rd NF:

A relation is in third normal form, if it is in 2NF and every non-key attribute of the relation is non-transitively dependent on each candidate key of the relation.

In 4th NF:

A table is in fourth normal form (4NF) if and only if it is in Boyce-Codd Normal Form BCNF and contains no more than one multi-valued dependency. Denormalization :is the process of adding redundant data to speed up complex queries involving multiple table JOINS. One might just go to a lower form of Normalization to achieve Denormalization and better performance. Data is included in one table from another in order to eliminate the second table which reduces the number of JOINS in a query and thus achieves performance.

What is DDL?

Data Definition Language (DDL) is a standard for commands that define the different structures in a database. DDL statements create, modify, and remove database objects such as tables, indexes, and users. Common DDL statements are CREATE, ALTER, and DROP.

What is Join?

A JOIN is a means for combining fields from two tables (or more) by using values common to each.

What is Schema?

A schema is a collection of database objects (as far as this hour is concerned—tables) associated with one particular database username. This username is called the schema owner, or the owner of the related group of objects. You may have one or multiple schemas in a database.

What is class?

Define Data base. A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views and other objects.

What is redundancy?

Data redundancy is a condition created within a database or data storage technology in which the same piece of data is held in two separate places. This can mean two different fields within a single database, or two different spots in multiple software environments or platforms.

What is CRUD?

CRUD stands for Create, Read, Update and Delete. (Retrieve may occasionally be substituted for Read.)

What is View?

View is the result set of a stored query on the data, which the database users can query just as they would in a persistent database collection object. This pre-established query command is kept in the database dictionary