Interview Questions

Here is a list of some important and basic Interview Questions which are asked in many IT companies:

SECTION- 1: ETL/ DATAWAREHOUSE QUESTIONS

 

·         Discuss about the basic process which is involved in ETL Testing?

·         What is the difference between Functional Testing and ETL Testing?

·         What is SCD(Slowly Changing Dimensions) and its types?

·         Difference between a file and a table? Is there any difference between the structure of these?

·         What is a Factless Fact? Illustrate with an example.

·         Difference between .dat file and .csv file?

·         What is a data mart?

·         Discuss about various Data Warehousing Objects?

·         What do you mean by Junk Dimension?

·         How would you check the transformation rules applied in a particular scenario?

·         Difference between Star and Snowflake Schema?

·         What are the advantages of Type 2 Dimensions?

·         How to do data validation when Source is a flat file and Target is a MYSQL or Oracle?

·         What is Data Loading? How is it done? How will you ensure that all the data has been loaded correctly into the target data warehouse?

·         How to count the number of columns in a flat file i.e. how data count validation is done?

·         Why is Data warehouse Subject-oriented? Explain.

·         What is the difference between ODS and Staging Area?

·         How mapping is being checked in Information Power Center Tool? What is the use of Workflow manager?

·         What are Degenerated and Confirmed Dimensions?

·         What all ETL Automation tools are used?

·         What all Data Quality Checks are being applied during Transformation phase?

·         What is a Galaxy Schema?

·         Difference between Full and Incremental Extraction. Discuss various scenarios when to use them.

                                    
SECTION- 2: DATABASE QUESTIONS

·         What is a surrogate key? Benefits of Surrogate key?

·         Difference between Truncate, Delete and Drop.

·         What is TCL?

·         How to compare two tables in SQL?

·         What is the use of MINUS Query? How can you count the number of records with it?

·         How to get the last and first name in SQL?

·         How to display the employee with same name in SQL?

·         How to use Group by? Can we use Group by and where clause together? If yes, then how? If not, then why?

·          What is the use of Having clause?

·         What are the types of Joins?

·         How will you get 45 67 from a given string ‘1234567’?

·         Suppose there are two tables Table ‘A’ and Table ‘B’ .
Table A has 1 2 records and Table B has 1 2 3 4 records.
What will be the result after applying Left Join and Inner join?

·         Display the name, location & dept name of all employees earning more than 15000

·         Find out the difference between highest and lowest salaries.

·         LIST the names of the employees drawing the highest salary.

·         List all employee details whose salary is greater than Avg salary of employees whose hire date is before 01-04-91.

·         List the job with highest AVG salary.  

·         Find the details of the dept whose empnum=10.

·         Find the second max salary of all employees

  

SECTION- 3: UNIX QUESTIONS

·         How to use ls command in Unix?

·         How to find the length of a string?

·         To count total number of words in a string?

·         How to check whether the write permission is given to a file or not?

·         How to check the total number of users logged in?

·         Use of Head and Tail.

·         To delete a file if empty and read and write permission should be there.

·         To check the given file name is a directory or not?

·         Use of ‘grep’

·         To print from second till fifth line of a given file

·         To count the total number of lines using awk.

·         To print the third line of a given file

·         What is the use of find command

·         How can you change the permissions on the file? Give example.

·         Difference between chgrp and chown?