Top 10 interview questions for dot net developer - SQL

In this blog I am not going to write a big epic on how to crack interviews but just briefing on it in “write less, guess more, and understand most” manner. So directly coming to the point from below paragraph to save your time in reading essay (and off course mine too in writing )

I prefer categorizing the questions with appropriate weightage as per the current requirement for a resource.Generally I categories the things in 5 sections as –


[B] OOPS (relate it with C# or VB or language u use)

[C] .net related ( from basic to advance)

[D] AJAX  and miscellaneous related (using jQuery and JSON,  Ajax/Script manager/Update panel and SOAP , validations, plugins, jQuery selectors and usage etc., Cross domain data posting, etc )

[E] Particular framework/ technology related like WCF, MVC etc.

Starting with SQL section in "Top 10 interview questions asked for .net developer position” ;we will see other section's questions in next blogs.

Basic SQL:

  1. What kind of function can be written in SQL? How a function is differ from Stored procedure?
  2. What is trigger? Can you write the syntax for AFTER trigger?
  3. Have you ever used Magic tables? What are they? And where/how can be used?
  4. What is the difference between Temp table and Table variable?(a) Difference between local temp table and Gloabal temp table.
  5. What is Identity column type? Can we reset the value of column of this type? What will be the next value, (a) if we delete all the records from this table and insert a fresh new record? (b) if we delete the table (c) if we truncate the table
  6. What is the difference between Joins and Subqueries? Which one is better? Can you write the syntax for CROSS JOIN. (a) difference between Left join and Right join.
  7. How many types of Indexes can be done inSQL? What is the difference between them? Which one is the default type? Which one is better to use? (a) Can we have a table without any type of Indexes? (b) can you have a primary key on a table with non-clustered index?
  8. What is the difference in Primary key constraint and Unique key constraint? Is”Default” a constraint in SQL? (a) difference between varchar datatype and char datatype.
  9. When and How to use cursor with syntax.
  10. How to do SQL query optimization?


There may be few questions related to syntaxes and queries like “write a query to get the 5th highest paying salary” etc. So be prepare about this.


Wherever differences is asked, try to give atleast 3 differences. For example if you say” table variable doesn't maitain the transaction scope while temp table do” would be not enough to satisfy interviewer.