UrbanPro
true

Learn SQL Programming from the Best Tutors

  • Affordable fees
  • 1-1 or Group class
  • Flexible Timings
  • Verified Tutors

Search in

SQL Tips (4 to 6)

Umasankar Natarajan
07/07/2017 0 0

SQL tips 4:
Avoid INDEX, unless you need to retrieve information quickly. Index will slower insert and update data query.

The another way is using sub query

Select MAX(salary)
FROM employee
WHERE salary IN
(Select top 2 salary from employee where salary is not null order by salary desc)

==============================================
SQL tips 5:
NULL and ZLS (zero length string) both are different.

NULL means data is unknown or missing.

NULL should be checked with IS NULL or IS NOT NULL only. Comparison operator equal to (=) or not equal to (<>) should not be used.

ZLS should be checked with two single quotes  ('') together.                        

==============================================
SQL tips 6:
Always use primary key with integer field and unique key with string or text field.

This is not rule, it is best practice.

0 Dislike
Follow 0

Please Enter a comment

Submit

Other Lessons for You


What Is WorkTable In SQL Server?
What is WorkTable in SQL Server? USE AdventureWorks2014 GO SET STATISTICS IO ON GO SELECT * FROM Production.Product p CROSS JOIN Production.Product p1 GO If you run above query,...

How to work fast while working on MS Excel?
Many people struggle to find out the way on how they can work faster while working on MS Excel/Access or VBA. let me share the tip for that. If you are new or working since long time on Excel/Access...

An Introduction to Business Intelligence Concepts
Looking for a Business Intelligence (BI) solution for your company can be intimidating. BI uses its own special terminology and the database design concepts can be difficult to grasp. So where do you...

What Are Macros?
i. Macros are little programs that run within Excel and help automate common repetitive tasks. Macros are one of Excel's most powerful, yet underutilized feature. Using macros, you can save hours and boost...
X

Looking for SQL Programming Classes?

The best tutors for SQL Programming Classes are on UrbanPro

  • Select the best Tutor
  • Book & Attend a Free Demo
  • Pay and start Learning

Learn SQL Programming with the Best Tutors

The best Tutors for SQL Programming Classes are on UrbanPro

This website uses cookies

We use cookies to improve user experience. Choose what cookies you allow us to use. You can read more about our Cookie Policy in our Privacy Policy

Accept All
Decline All

UrbanPro.com is India's largest network of most trusted tutors and institutes. Over 55 lakh students rely on UrbanPro.com, to fulfill their learning requirements across 1,000+ categories. Using UrbanPro.com, parents, and students can compare multiple Tutors and Institutes and choose the one that best suits their requirements. More than 7.5 lakh verified Tutors and Institutes are helping millions of students every day and growing their tutoring business on UrbanPro.com. Whether you are looking for a tutor to learn mathematics, a German language trainer to brush up your German language skills or an institute to upgrade your IT skills, we have got the best selection of Tutors and Training Institutes for you. Read more