Important Interview Questions of Database

• What is database or database management systems (DBMS)?
• What is SQL?
• What’s difference between DBMS and RDBMS?
• What are CODD rules?
• What are E-R diagrams?
• How many types of relationship exist in database designing?
• What is normalization? What are different type of normalization?
• What is denormalization?
• Can you explain Fourth Normal Form?
• Can you explain Fifth Normal Form?
• What’s the difference between Fourth and Fifth normal form?
• Have you heard about sixth normal form?
• What are DML and DDL statements?
• How do we select distinct values from a table?
• What is like operator for and what are wild cards?
• Can you explain Insert, Update and Delete query?
• What is order by clause?
• What is the SQL In clause?
• Can you explain the between clause?
• I have an employee salary table how do we find the second highest from it?
• What are different types of joins in SQL?
• What is “CROSS JOIN”?
• You want to select the first record in a given set of rows?
• What is the default “SORT” order for a SQL?
• What is a self-join?
• What’s the difference between DELETE and TRUNCATE?
• What are Wildcard operators?
• What is like clause in SQL?
• What’s the difference between “UNION” and “UNION ALL”?
• What are cursors and what are the situations you will use them?
• What are the steps to create a cursor?
• What is “Group by” clause?
• What is the difference between “HAVING” and “WHERE” clause?
• What is a Sub-Query?
• What are Aggregate and Scalar Functions?
• Can you explain the SELECT INTO Statement?
• What is a View?
• What is “Correlated Sub queries”?
• What is SQl injection?
• What is “Data Warehousing”?
• What are Data Marts?
• What are Fact tables and Dimension Tables?
• What is Dimensional Modeling?
• What is Star Schema Design?
• What is Snow Flake Schema design in database?
• What’s the difference between Star and Snow flake schema?
• What is ETL process in Data warehousing?
• What are the different stages in “Data warehousing”?
• What is “Data mining”?
• Compare “Data mining” and “Data Warehousing”?
• What are indexes?
• What are B-Trees?
• I have a table which has lot of inserts, is it a good database design to create indexes on that table?
• Insert’s are slower on tables which have indexes, justify it?
• Why do page splitting happen?
• What are “Table Scan’s” and “Index Scan’s”?
• What are the two types of indexes and explain them in detail?
• What’s the difference between clustered and non-clustered indexes?