Interview Q&A

• Differences between star and snowflake schemas

  Star schema A single fact table with N number of Dimension Snowflake schema Any dimensions with extended dimensions are know as snowflake schema

• What are Data Marts

  A data mart is a focused subset of a data warehouse that deals with a single area(like different department) of data and is organized for quick analysis

• What is a Fact,Dimension,Measure?

  Fact is key performance indicator to analyze the business.Dimension is used to analyze the fact.Without dimension there is no meaning for fact.

• What are the different types of data warehousing?

  Types of data warehousing 1. Enterprise Data warehousing 2. ODS (Operational Data Store) 3. Data Mart

• What is a scope resolution operator?

  A scope resolution operator (::) can be used to define the member functions of a class outside the class.Most generally a scope resolution operator is required when a data member is redefined by a derived class, or an overriden method of t...

• What do you mean by inline function?

  The idea behind inline functions is to insert the code of a called function at the point where the function is called. If done carefully, this can improve the application's performance in exchange for increased compile time and possibly (b...

• What is virtual class and friend class?

  Virtual Base Class: Used in context of multiple inheritance in C++.Friend class: When a class declares another class as its friend, it is giving complete access to all its data and methods including private and protected data and methods to...

• Difference between realloc() and free()?

  Realloc() is used to reallocate the memory for variable.Realloc()used to resize the memory held by the pointer to the number of bytes specificed.If the new size is larger than current size, new memory is allocated. If it is less, the remai...

• What is an object?

  In C++, Object is an instance of a Class that has a runtime state, and is associated with certain specific methods that can change its state.

• What is a class?

  class is a user defined data type,in which data members and member functions are defined.A class can also be defined as a classification/category of objects that have similar attributes and behaviour.For example, Automobile is a category o...

• What is data structure?

  A data structure is a way of organizing data that considers not only the items stored, but also their relationship to each other. Advance knowledge about the relationship between data items allows designing of efficient algorithms for the m...

• What is the bucket size, when the overlapping and collision occur at the same time?

  The answer is one. If there is only one entry possible in the bucket, when the collision occurs, there is no way to accommodate the colliding value. This results in the overlapping of values.

• There are 8, 15, 13, and 14 nodes in four different trees. Which one of them can form a full binary tree?

  The answer is the tree with 15 nodes. In general, there are 2^n-1 nodes in a full binary tree. By the method of elimination: Full binary trees contain odd number of nodes, so there cannot be full binary trees with 8 or 14 nodes. Moreover,...

• n an AVL tree, at what condition the balancing is to be done?

  If the "pivotal value", or the "height factor", is greater than one or less than minus one.

• What are some of the applications for the tree data structure?

  1- Manipulation of the arithmetic expressions. 2- Symbol table construction. 3- Syntax analysis.

• Which data structure is used to perform recursion?

  The answer is Stack. Stack has the LIFO (Last In First Out) property; it remembers it's ‘caller’. Therefore, it knows to whom it should return when the function has to return. On the other hand, recursion makes use of the system stack for...

• Which data structure is used to perform recursion?

  The answer is Stack. Stack has the LIFO (Last In First Out) property; it remembers it's ‘caller’. Therefore, it knows to whom it should return when the function has to return. On the other hand, recursion makes use of the system stack for...

• What is the minimum number of queues needed to implement the priority queue?

  Two. One queue is used for the actual storing of data, and the other one is used for storing the priorities.

• What pointer type is used to implement the heterogeneous linked list in C?

  The answer is the void pointer. The heterogeneous linked list contains different data types in it's nodes and we need a link, pointer, to connect them. Since we can't use ordinary pointers for this, we use the void pointer. Void pointer is...

• What is the use of TRT instruction and how it is working?

  TRT is used to scan a string of characters, searching for the occurrence of any the characters which are specified in a translate table.

• Define the terms Parent & Child?

  Parent-Any segment that has one or more segments directly below it is a Parent. Child-Any segment that has segment directtly above it is called the Child.

• What is a database record?

  A single occurence of the root along with all its dependents is called the database record.

• How man key fields and search fields can a segment have?

  One key field and as many search fields in the segment can be declared.

• What is Skeleton Cursor Table (SKCT)?

  The Executable form of a Plan. This is stored in SYSIBM.SCT02 table.

• How many buffer bools are available in DB2?

  Ten 32K size bufferpools and fifty 4K size buffer pools (BP0 to BP49). Default buffer pools are BP0, BP1, BP2 & BP32

• How do you restart a proc from a particular step?

  In job card, specify RESTART=proc step step name where procstep = name of the jcl step that invoked the proc and stepname = name of the proc step where you want execution to start

• What is primary allocation for a Data Set?

  The space allocated when the Data Set is first created

• What is a cluster?

  A cluster is the combination of the index, sequence set and data portions of the dataset. The operating system gives program access to the cluster, ie. to all parts of the dataset simultaneously.

• What are the types of VSAM datasets?

  Entry sequenced datasets (ESDS), key sequenced datasets (KSDS) and relative record dataset (RRDS).

• What is the difference between physical map and symbolic map?

  The physical map is the load module and the symbolic map is the data structure

• What is the use of EVALUATE statement?

  Evaluate is like a case statement and can be used to replace nested Ifs. The difference between EVALUATE and case is that no 'break' is required for EVALUATE i.e. control comes out of the EVALUATE as soon as one match is made.

• How do you define a sort file in JCL that runs the COBOL program?

  Use the SORTWK01, SORTWK02,..... dd names in the step. Number of sort datasets depends on the volume of data being sorted, but a minimum of 3 is required.

• What is binary search?

  Search on a sorted array. Compare the item to be searched with the item at the center. If it matches, fine else repeat the process with the left half or the right half depending on where the item lies.

• What is the difference between SEARCH and SEARCH ALL?

  SEARCH - is a serial search. SEARCH ALL - is a binary search & the table must be sorted ( ASCENDING/DESCENDING KEY clause to be used & data loaded in this order) before using SEARCH ALL.

• What is the difference between index and subscript?

  Subscript refers to the array occurrence while index is the displacement (in no of bytes) from the beginning of the array. An index can only be modified using PERFORM, SEARCH & SET.

• What does the INITIALIZE verb do?

  Alphabetic, Alphanumeric fields & alphanumeric edited items are set to SPACES. Numeric, Numeric edited items set to ZERO.

• What are the different data types available in COBOL?

  Alpha-numeric (X), alphabetic (A) and numeric (9).

• Name the divisions in a COBOL program.

  IDENTIFICATION DIVISION, ENVIRONMENT DIVISION, DATA DIVISION, PROCEDURE DIVISION.

• Name the divisions in a COBOL program.

  IDENTIFICATION DIVISION, ENVIRONMENT DIVISION, DATA DIVISION, PROCEDURE DIVISION.

• Explain the difference between MyISAM Static and MyISAM Dynamic.

  In MyISAM static all the fields have fixed width. The Dynamic MyISAM table would include fields such as TEXT, BLOB, etc. to accommodate the data types with various lengths. MyISAM Static would be easier to restore in case of corruption, sin...

• What is SERIAL data type in MySQL?

  BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT

• What are HEAP tables in MySQL?

  HEAP tables are in-memory. They are usually used for high-speed temporary storage. No TEXT or BLOB fields are allowed within HEAP tables. You can only use the comparison operators = and . HEAP tables do not support AUTO_INCREMENT. Indexes m...

• What’s the default port for MySQL Server?

  3306

• Explain the difference between mysql and mysqli interfaces in PHP?

  mysqli is the object-oriented version of mysql library functions.

• How do you start and stop MySQL on Windows?

  net start MySQL, net stop MySQL

• What is difference between UNIQUE and PRIMARY KEY constraints

  A table can have only one PRIMARY KEY whereas there can be any number of UNIQUE keys. The columns that compose PK are automatically define NOT NULL, whereas a column that compose a UNIQUE is not automatically defined to be mandatory must al...

• What is difference between Rename and Alias

  Rename is a permanent name given to a table or column whereas Alias is a temporary name given to a table or column which do not exist once the SQL statement is executed.

• What are different Oracle database objects

  TABLES VIEWS INDEXES SYNONYMS SEQUENCES TABLESPACES etc

• What are various constraints used in SQL

  NULL NOT NULL CHECK DEFAULT

• What are various joins used while writing SUBQUERIES

  Self join-Its a join foreign key of a table references the same table. Outer Join–Its a join condition used where One can query all the rows of one of the tables in the join condition even though they don’t satisfy the join condition. Equ...