Master SQL interviews (Top Interview questions & answers)

Course Curriculum

Chapter 1: Most important SQL Interview questions and answers

Lecture 1: Question 1: What is a Database?

Lecture 2: Question 2: What is the difference between a database and DBMS?

Lecture 3: Question 3: What is the difference between DBMS and Relational DBMS?

Lecture 4: Question 4. What are DDL, DML and DCL statements?

Lecture 5: Question 5: What is SQL?

Lecture 6: Question 6: How do you create a table?

Lecture 7: Question 7: What is the difference between CHAR and VARCHAR2 datatype in sql

Lecture 8: Question 8: How do you create a table from another table?

Lecture 9: Question 9: How do you insert values into a table?

Lecture 10: Question 10: Can you insert data into the same table by taking data from it?

Lecture 11: Question 11: What will happen if you insert a bigger value into a varchar column

Lecture 12: Question 12: How do you select data from a table?

Lecture 13: Question 13: How do you select data from a table using WHERE clause?

Lecture 14: Question 14: How do you delete all data from a table?

Lecture 15: Question 15: How do you delete data from a table based on a condition?

Lecture 16: Question 16: What is the difference between DELETE and TRUNCATE statements?

Lecture 17: Question 17: How do you drop a table?

Lecture 18: Question 18: What is the difference between Delete and Drop?

Lecture 19: Question 19: What are constraints and what is their importance?

Lecture 20: Question 20: What is a Primary Key?

Lecture 21: Question 21: How do you create a Primary key while creating a table?

Lecture 22: Question 22: How do you create a table level Primary Key?

Lecture 23: Question 23: How do you create a Unique Key while creating a table?

Lecture 24: Question 24: How do you create a table level Unique Key?

Lecture 25: Question 25: What is the difference between a Primary Key and Unique Key?

Lecture 26: Question 26: How do you create a Check constraint while creating a table?

Lecture 27: Question 27: How do you create a table level check constraint?

Lecture 28: Question 28: Create a check constraint to restrict values to a range

Lecture 29: Question 29: Create a check constraint to have name starting with A

Lecture 30: Question 30: How do you create a foreign key on a table?

Lecture 31: Question 31: How do you create a table level foreign key?

Lecture 32: Question 32: What is meant by a nullable column?

Lecture 33: Question 33: What are aggregate functions?

Lecture 34: Question 34: Write a SQL statement to count the total number of rows of a table

Lecture 35: Question 35: Write a SQL statement to count number of rows matching a condition

Lecture 36: Question 36: Write a SQL statement where column matches with a string value(LIKE

Lecture 37: Question 37: How do you calculate the average,minimum and maximum salary from em

Lecture 38: Question 38: How do you calculate total salary for employees grouped by employee

Lecture 39: Question 39: How do you select data in a table in sorted order(Asc & and desc)

Lecture 40: Question 40: How do you specify a condition with a GROUP BY clause?

Lecture 41: Question 41: Can you have both HAVING and WHERE clauses together?

Lecture 42: Question 42: Write a query to display schema of a table

Lecture 43: Question 43: Alter a table to add a new column to a table

Lecture 44: Question 44: How do you change the data type of a column of a table

Lecture 45: Question 45: How do you drop a column from a table?

Lecture 46: Question 46: What is a Join?

Lecture 47: Question 47: Explain different types of joins

Lecture 48: Question 48: What is the difference between an outer join and inner join?

Lecture 49: Question 49: What is the difference between Left Inner Join and Left Outer join?

Lecture 50: Question 50: What is Cross Join? Where is it useful?

Lecture 51: Question 51: What is Full Join?

Lecture 52: Question 52: What is Self Join?

Lecture 53: Question 53: Write a sql statement to display current date and time

Lecture 54: Question 54: Write a sql statement to display the server and database name

Lecture 55: Question 55: Write a sql statement to display the user name

Lecture 56: Question 56: Write a sql statement to display the number of tables present in db

Lecture 57: Question 57: Write sql to display the second highest salary from employee table

Lecture 58: Question 58: Write a SQL query to return a substring from a string

Lecture 59: Question 59: Write a SQL query to return the no of characters of a given string

Lecture 60: Question 60: Write SQL to return the numeric position of a character in a string

Lecture 61: Question 61: Write a SQL statement to display distinct salaries from a table

Lecture 62: Question 62: How do you concatenate two strings in sql?

Lecture 63: Question 63: Create a empty table with the same structure as another table

Lecture 64: Question 64: SQL to return first 3 characters(right and middle also) of a string

Lecture 65: Question 65: What are indexes? Why they are used?

Lecture 66: Question 66: What are clustered indexes?

Lecture 67: Question 67: What are non-clustered index?

Lecture 68: Question 68: What is a Unique index? Write a SQL to create one

Lecture 69: Question 69: What is a view? Write a sql statement to create a view

Lecture 70: Question 70: Write a sql statement to display the number of views present

Lecture 71: Question 71: What is a subquery? Why is it used?

Lecture 72: Question 72: Write a query to remove spaces present in a string from sides

Lecture 73: Question 73: What is the difference between Union and Union all?

Lecture 74: Question 74: What is EXCEPT or MINUS operator?

Lecture 75: Question 75: What is Intersect operator?

Lecture 76: Question 76: What are temp tables in SQL Server?

Lecture 77: Question 77: What are global temp tables in SQL?

Lecture 78: Question 78: How to get nth maximum salary from a table?

Lecture 79: Question 79: Nth maximum salary when there are duplicate salaries

Lecture 80: Question 80: What is COALESCE function in SQL?

Lecture 81: Question 81: What is OLTP?

Lecture 82: Question 82: What is the difference between OLTP and OLAP systems?

Lecture 83: Question 83: What are the different types of relationship existing in RDBMS?

Lecture 84: Question 84: How to create a temp table in SQL Server?

Lecture 85: Question 85: How to write a CASE statement in SQL?

Lecture 86: Question 86: How do we delete duplicate rows?