SQL Interview Questions and Answers Archives - Page 43 of 67

Interview Question of the Week #020 – What is the Difference Between DISTINCT and GROUP BY?

May 17, 2015

SQL, SQL Interview Questions and Answers, SQL Server, SQL Tips and Tricks

Question: What is the Difference Between DISTINCT and GROUP BY? Answer: A DISTINCT and GROUP BY usually generate the same query plan, so performance should be the same across both query constructs. GROUP BY should be used to apply aggregate operators to each group. If all you need is to remove duplicates,…

Interview Question of the Week #019 – How to Reset Identity of Table

May 10, 2015

Pinal Dave

SQL, SQL Interview Questions and Answers, SQL Server, SQL Tips and Tricks

SQL Scripts

Here is the question which I received in email: Question: I have a table which has an identity column. I have recently deleted old and archive it to another place. Now I want to reset the identity of the table to original value of 1. How should I do that? Answer:…

Interview Question of the Week #018 – Script to Remove Special Characters – Script to Parse Alpha Numerics

May 3, 2015

Pinal Dave

SQL, SQL Interview Questions and Answers, SQL Server, SQL Tips and Tricks

SQL Function, SQL Scripts

If you ask me – there are certain questions not appropriate for an interview as they are often very subjective. There are some questions, which really do not help to identify if the candidate has the necessary skills or not. Here is one such question, if you ask me in the…

Interview Question of the Week #017 – Performance Comparison of Union vs Union All

April 26, 2015

Pinal Dave

SQL, SQL Interview Questions and Answers, SQL Server, SQL Tips and Tricks

SQL Union clause, Union

Here is what I just learned from email. One of the very prestigious organization asks one of their candidate following questions – Question: If you have options to use Union or Union All – which one of the option will use keeping performance as a top most requirement for the query. Answer: Though…

Interview Question of the Week #016 – How to Take Database Offline

April 19, 2015

Pinal Dave

SQL, SQL Interview Questions and Answers, SQL Server, SQL Tips and Tricks

SQL Scripts

Here is the question, I received in the recent conference where I was presenting on Database Technology. Question: What does it mean by Taking Database Offline and How to do it? Answer: Taking database offline means, it will be no more available for database operations. Here are is how you…

Interview Question of the Week #015 – How to Move TempDB to Different Drive

April 12, 2015

Pinal Dave

SQL Interview Questions and Answers

SQL TempDB

Here is one of the most popular questions I often come across- Question – How to move the TempDB to different drive when the log files are filled? Answer – In most of the cases which I have observed one has to move the TempDB to different drive when TempDB log…

Interview Question of the Week #014 – How to DELETE Duplicate Rows

April 5, 2015

Pinal Dave

SQL, SQL Interview Questions and Answers, SQL Server, SQL Tips and Tricks

Here is another very common question I often received, which candidates face in the interview. Question: How to delete duplicate rows in SQL Server (considering there is an identity column in table)? Answer: Well, there is no better answer than following a script. If you ask me this question in…