SQL Basic
SQL HOMESQL Intro
SQL Syntax
SQL Select
SQL Distinct
SQL Where
SQL And & Or
SQL Order By
SQL Insert
SQL Update
SQL Delete
SQL Demo
SQL Try ItSQL Advanced
SQL TopSQL Like
SQL Wildcards
SQL In
SQL Between
SQL Alias
SQL Joins
SQL Inner Join
SQL Left Join
SQL Right Join
SQL Full Join
SQL Union
SQL Select Into
SQL Create DB
SQL Create Table
SQL Constraints
SQL Not Null
SQL Unique
SQL Primary Key
SQL Foreign Key
SQL Check
SQL Default
SQL Create Index
SQL Drop
SQL Alter
SQL Increment
SQL Views
SQL Dates
SQL Nulls
SQL isnull()
SQL Data Types
SQL Functions
SQL FunctionsSQL avg()
SQL count()
SQL first()
SQL last()
SQL max()
SQL min()
SQL sum()
SQL Group By
SQL Having
SQL ucase()
SQL lcase()
SQL mid()
SQL len()
SQL round()
SQL now()
SQL format()
SQL Quick Ref
SQL Hosting
SQL Summary
SQL Quiz
SQL QuizSQL NULL Functions
SQL ISNULL(), NVL(), IFNULL() and COALESCE() Functions
Look at the following "Products" table:
| P_Id | ProductName | UnitPrice | UnitsInStock | UnitsOnOrder |
|---|---|---|---|---|
| 1 | Jarlsberg | 10.45 | 16 | 15 |
| 2 | Mascarpone | 32.56 | 23 | |
| 3 | Gorgonzola | 15.67 | 9 | 20 |
Suppose that the "UnitsOnOrder" column is optional, and may contain NULL values.
We have the following SELECT statement:
FROM Products
In the example above, if any of the "UnitsOnOrder" values are NULL, the result is NULL.
Microsoft's ISNULL() function is used to specify how we want to treat NULL values.
The NVL(), IFNULL(), and COALESCE() functions can also be used to achieve the same result.
In this case we want NULL values to be zero.
Below, if "UnitsOnOrder" is NULL it will not harm the calculation, because ISNULL() returns a zero if the value is NULL:
SQL Server / MS Access
FROM Products
Oracle
Oracle does not have an ISNULL() function. However, we can use the NVL() function to achieve the same result:
FROM Products
MySQL
MySQL does have an ISNULL() function. However, it works a little bit different from Microsoft's ISNULL() function.
In MySQL we can use the IFNULL() function, like this:
FROM Products
or we can use the COALESCE() function, like this:
FROM Products
| WEB HOSTING |
|---|
| Best Web Hosting |
| PHP MySQL Hosting |
| Best Hosting Coupons |
| UK Reseller Hosting |
| Cloud Hosting |
| Top Web Hosting |
| $7.95/mo SEO Hosting |
| Premium Website Design |
| WEB BUILDING |
|---|
| XML Editor - Free Trial! |
| FREE Website BUILDER |
| Free Website Templates Free CSS Templates |
| Make Your Own Website |
| W3SCHOOLS EXAMS |
|---|
|
Get Certified in: HTML, CSS, JavaScript, XML, PHP, and ASP |
| W3SCHOOLS BOOKS |
|---|
|
New Books: HTML, CSS JavaScript, and Ajax |
| STATISTICS |
|---|
|
Browser Statistics Browser OS Browser Display |
| SHARE THIS PAGE |
|---|
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.