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infosys technical (6 DBMS (List different advantages of DBMS (A database…

- - - - Improved data sharing
      - 2 Minimized data inconsistency
      - 3 Improved data security
      - 4 Improved data access
  - - - 1 Physical:
        
        lowest level of data abstraction. It tells us how the data is actually stored in memory.
      - 2 Logical:
        
        information that is actually stored in the database in the form of tables
      - 3 View
        
        Only a part of the actual database is viewed by the users.
        
        Users can just view the data and interact with the database, storage and implementation details are hidden from them.
  - - - both ASCII character data types and almost same but they are different at the stage of storing and retrieving the data from the database.
        
        in mysql
        
        CHAR (character) Data Type
        
        It can hold a maximum of 255 characters.
        
        uses static memory allocation.
        
        VARCHAR (variable character) Data Type
        
        It can hold a maximum of 65,535 characters
        
        uses dynamic memory allocation.
  - - - is a database management system (DBMS) similar to a relational database, but with an object-oriented database model: objects, classes and inheritance are directly supported in database schemas and in the query language.
  - - - The formal definition of database schema is a set of formulas (sentences) called integrity constraints imposed on a database.
      - 5.1
        
        what are the different levels of database schema?
        
        Conceptual schema- a map of concepts and their relationships.
        Logical schema- a map of entities and their attributes and relations
        Physical schema- a particular implementation of a logical schema
        Schema object- Oracle database object
  - - - 6
        
        what is difference between foreign key and reference key ?
        
        Reference Key is the primary key that is referenced in the other table (linked via the other tables Foreign Key). Foreign Key is how you link the second table to the primary tables Primary Key (or Reference Key).
  - - - 7 and above
        
        7
        
        Tell me about DSN
        
        A data source name (DSN) is a data structure that contains the information about a specific database that an Open Database Connectivity ( ODBC ) driver needs in order to connect to it.
        
        8
        
        Structural difference between bitmap and b-tree index
        
        B-tree and Bitmap indexes are internally different but functionally they are same in retrieving rows faster than a full-table scan.
        
        Bitmap indexes are used on the columns which has lots of duplicate values(low cardinality) while B-tree indexes are useful when there is less or no duplicate values (high cardinality).
        
        B-tree index uses a tree-like structure with index nodes, where Bitmap index uses a two dimensional array with zeros and ones (bits) values.
        
        1 more item...
        
        9
        
        Difference between Clustered index and non clustered index
        
        Clustered Index
        
        Only one per table
        
        Faster to read than non clustered as data is physically stored in index order
        
        Non Clustered Index
        
        Can be used many times per table
        
        Quicker for insert and update operations than a clustered index
        
        10
        
        keys in SQL?
        
        candidate key acts as a unique key. A unique key can be a Primary key. A candidate key can be a single column or combination of columns. Multiple candidate keys are allowed in a table.
        
        To uniquely identify a row, Primary key is used.
        A table allows only one Primary key
        A Primary key can be a single column or combination of columns.
        
        foreign key
        
        A foreign key in a table is a key which refer another tables primary key . A primary key can be referred by multiple foreign keys from other tables. It is not required for a primary key to be the reference of any foreign keys. The interesting part is that a foreign key can refer back to the same table but to a different column. This kind of foreign key is known as self-referencing foreign key.
        
        11
        
        Explain about Joins, Views, Normalization, Triggers?
        
        The JOIN keyword is used in an SQL statement to query data from two or more tables, based on a relationship between certain columns in these tables.
        Tables in a database are often related to each other with keys.
        
        A view is a virtual table.A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.
        You can add SQL functions, WHERE, and JOIN statements to a view and present the data as if the data were coming from one single table.
        
        Normalization is the process of efficiently organizing data in a database. There are two goals of the normalization process: eliminating redundant data (for example, storing the same data in more than one table) and ensuring data dependencies make sense (only storing related data in a table). Both of these are worthy goals as they reduce the amount of space a database consumes and ensure that data is logically stored.
        
        First Normal Form (1NF)
        
        Eliminate duplicative columns from the same table.
        
        Second Normal Form (2NF)
        
        further addresses the concept of removing duplicative data:
        
        Boyce-Codd Normal Form (BCNF or 3.5NF)
        
        Every determinant must be a candidate key.
        
        Fourth Normal Form (4NF)
        
        A relation is in 4NF if it has no multi-valued dependencies.
- - - - versions of internet protocol where IPv6 is the enhanced version of IPv4.
        
        IPv4
        
        It can generate 4.29 x 10^9 addresses.
        
        32 bits (4 bytes)
        
        In decimal
        
        End-to-end connection integrity unachievable
        
        IPV6
        
        3.4 x 10^38.
        
        128 bits (16 bytes)
        
        In hexadecimal
        
        End-to-end connection integrity achievable
  - - - Session is a Logical Connectivity between the source and destination
  - - - The default gateway commonly connects the internal networks and the outside network (Internet).
        
        could also act as a proxy server and a firewall.
- - - - C++ is platform-dependent.
        
        Java is platform-independent.
      - C++ supports multiple inheritance.
        
        Java doesn't support multiple inheritance through class. It can be achieved by interfaces in java.
      - C++ supports both call by value and call by reference.
        
        Java supports call by value only. There is no call by reference in java.
      - C++ supports structures and unions.
        
        Java doesn't support structures and unions.
    - - means that you can run the same code with little or no modification on multiple platforms.
    - - What do you know about Unix and DOS?
        
        DOS and UNIX are two operating systems that are predominantly text based.
        
        DOS was meant to be an operating system for personal computers and sacrificed security to make it easier to use.
        
        The primary advantage of UNIX over DOS is its security. adds to the complexity of the operating system,
    - - MACHINE LANGUAGES
        
        made up of a series of binary patterns
        
        can be run directly
      - ASSEMBLY LANGUAGES:
        
        easier for the human
        
        machine language instructions are replaced with simple pneumonic abbreviations e.g., ADD, MOV
        
        requires translation to machine language.
        
        accomplished by a computer program known as an Assembler. Assemblers are written for each unique machine language.
      - HIGH LEVEL LANGUAGES
        
        like C,C++, JAVA etc., are more English-like
        
        translation is accomplished by either a compiler or an interpreter.
    - - 6 What is difference and similarity between C and C++ ?
        
        difference
        
        c
        
        developed by Dennis Ritchie
        
        C is a subset of C++.
        
        C contains 32 keywords.
        
        1 more item...
        
        c++
        
        C++ was developed by Bjarne Stroustrup
        
        C is a superset of C++.
        
        C contains 52 keywords.
        
        1 more item...
        
        Similarities
        
        similar syntax.
        
        model of both is very close to the hardware.
        
        Same notions of stack, heap, file-scope and static variables are present in both the languages.
        
        C++ has a slightly extended grammar than C, but the basic grammer is the same.
    - - 7 Differentiate between 'a' and "a".
        
        'a'
        
        'a' is a character literal. It's of type char, with the value 97 on most systems
        
        "a"
        
        "a" is a string literal. It's of type const char[2], and refers to an array of 2 chars with values 'a' and '\0'. In most, but not all, contexts, a reference to "a" will be implicitly converted to a pointer to the first character of the string.
        
        Both
        cout<< 'a'
        cout<< "a"
        Produce same result
        
        The first prints a single character value. The second successively prints all the characters of the string (except for the terminating '\0') -- which happens to be the single character 'a'.
    - - 8 What is preprocessor?
        
        Preprocessing is the first step of the language processing system. Language processing system translates the high level language to machine level language or absolute machine code
        
        Removing comments
        
        File inclusion
        
        Macro expansion
    - - 9
        
        9 Difference between Macro and ordinary definition.
        
        Macro takes parameters where as ordinary definition does
        not.
        
        Based on the parameter values to macro it can result in
        different value at run time. Ordinary defination value
        remains same at all place at run time.
        
        Macro can be used for conditional operations where as
        definition can not.
        
        Using macro one can achieve inline functionality in C ie. macro can be a function performing simple operations. not possible using definitions.
    - - 10 and above
        
        10 and above
        
        10
        
        difference between an EXE and a DLL?
        
        1.EXE is an extension used for executable files while DLL is the extension for a dynamic link library.
        
        2.An EXE file can be run independently while a DLL is used by other applications
        
        2 more items...
- - - - The capability of a class to derive properties and characteristics from another class is called Inheritance.
        
        Sup class
        
        Sub Class
      - Types of Inheritance
        
        1 Single Inheritance
        
        class subclass_name : access_mode base_class
        {
        //body of subclass
        };
        
        2 Multiple Inheritance:
        
        class subclass_name : access_mode base_class1, access_mode base_class2, ....
        {
        //body
        };
        
        Multilevel Inheritance:
        
        4 Hierarchical Inheritance:
        
        5 Hybrid (Virtual) Inheritance:
    - - abstraction focuses on the behavior of an object. On the other hand, encapsulation focuses on theimplementation of an object's behavior.
        
        Through encapsulation only we are able to enclose the components of the object into a single unit and separate the private and public members. It is through abstraction that only the essential behaviors of the objects are made visible to the outside world.
        
        we can say that encapsulation is the way to implement data abstraction. For example in class Student, only the essential information like roll no, name, date_of_birth, course, etc. of the student will be visible. The secret information like calculation of grades, allotment of examiners etc. will be hidden.
    - - 4 Define polymorphism.
        
        means having many forms
        
        C++ polymorphism is mainly divided into two types:
        
        Compile time polymorphism
        
        achieved by function overloading or operator overloading.
        
        Runtime polymorphism:
        
        achieved by Function Overriding.
- - - - Functions, classes, structures implements modularity in C++.
      - The concept of modular programming simple. It is an element of programming style that divides a single program into distinct parts called modules, each module being responsible for only one function or set of functions
    - - A token is the smallest element of a C++ program that is meaningful to the compiler.
      - C++ parser recognizes these kinds of tokens: identifiers, keywords, literals, operators, punctuators, and other separators.
    - - 1 Members of a class are private by default and members of a struct are public by default.
      - 2) When deriving a struct from a class/struct, default access-specifier for a base class/struct is public. And when deriving a class, default access specifier is private
        
        https://www.geeksforgeeks.org/structure-vs-class-in-cpp/
      - 3 A class is a reference type.
        
        .A struct is a value type.
      - 4 A structure couldn't have a destructor such as a class.
      - 5 You can't use sizeof with classes but you can with structures.
- - - - linear data structure, in which the elements are not stored at contiguous memory locations. The elements in a linked list are linked using pointer
    - - Stores the value of the variable of homogeneous datatype.
        
        Store the address of the another variable of same datatype as the pointer variable's datatype.
      - An array can store the number of elements, mentioned in the size of array variable.
        
        A pointer variable can store the address of only one variable at a time.
      - declaration
    - - algorithms that involve efficient data structure is applied in the following areas:
        
        numerical analysis, operating system, A.I., compiler design, database management, graphics, and statistical analysis
    - - Tell how to check whether a linked list is circular.
        
        While(pointer1)
        {
        pointer1=pointer->next;
        pointer2=pointer->next;
        if(pointer2->next)
        {
        pointer2=pointer->next;
        }
        if(pointer2==pointer1)
        {
        printf("Circular");
        }
        }
    - - 5
        
        Why is it difficult to store linked list in an array
        
        Linked list provide dynamic size while the size of array is fixed, So we must know the upper limit on the number of elements in advance
        
        Random access is not allowed. We have to access elements sequentially starting from the first node. So we cannot do binary search with linked lists.
        
        Extra memory space for a pointer is required with each element of the list.
- - - - Gray box testing
        
        programming partially known.
        
        Not suited to algorithm testing.
      - white box
        
        Suited to algorithm testing
      - Black box
        
        Not suited to algorithm testing.
        
        can be done by trial and error method.
        
        Least time consuming and exhaustive.
    - - 2 Give different types of software model. Which model is best amongst them?
        
        BASIC STAGES OF SOFTWARE DEVELOPMENT LIFE CYCLE
        
        Stage 1. Planning and requirement analysis
        
        Stage 2. Designing project architecture
        
        Stage 3. Development and programming
        
        Stage 4. Testing
        
        1 more item...
        
        SDLC MODELS
        
        Waterfall SDLC model
        
        Iterative SDLC Model
        
        Spiral SDLC Model
        
        V-shaped SDLC Model
        
        Agile SDLC Model
        
        most used?
        
        if you want to do something like a simple calculator waterfall its ok . Agile its the most used by big companies.
- - - - Write a program in C to swap two numbers without using a third variable.
        
        int x = 10, y = 5;
        
        x = x + y; // x now becomes 15
        
        y = x - y; // y becomes 10
        
        x = x - y; // x becomes 5
    - - 2 Write a program to decide whether the input number is a prime number or not.
        
        https://pastebin.com/aDk77pNU
    - - Given an array of 1s and 0s arrange the 1s together and 0s together in a single scan of the array. Optimize the boundary conditions.
        
        https://pastebin.com/9SdkNEnt