ISNULL function in SQL Server

In SQL Server, the ISNULL function allows you to return an alternate value when an input expression is NULL. This article will show you in detail how to use the ISDATE function handler with syntax and specific examples to make it easier to visualize and capture functions.

Describe

The ISNULL function in SQL Server returns a specified value if the expression is NULL. If the expression is not NULL then the function returns the expression itself.

Syntax

To use the ISNULL statement in SQL Server, we use the following syntax:

 ISNULL(bieuthuc, giatri_thaythe) 

Parameters :

1. bieuthuc: any expression should check whether it is NULL or not.
2. giatri_thaythe: is a return value instead of bieuthuc = NULL, giatri_thaythe must be of the same data type as bieuthuc.

Note :

1. The ISNULL function returns giatri_thaythe if the expression is NULL.
2. The ISNULL function returns bieuthuc if the expression is not NULL .
3. The ISNULL function can be used in later versions of SQL Server: SQL Server 2017, SQL Server 2016, SQL Server 2014, SQL Server 2012, SQL Server 2008 R2, SQL Server 2008, and SQL Server 2005.

For example

See how to use the ISNULL statement in SQL Server.

 SELECT ISNULL(NULL, 'TipsMake.com'); 
 Result: 'TipsMake.com' 
 
 SELECT ISNULL('TipsMake.com', 'QuanTriMang'); 
 Result: 'TipsMake.com' 
 
 SELECT ISNULL(NULL, 45); 
 Result: 45 
 
 SELECT ISNULL(12, 45); 
 Result: 12 
 
 SELECT ISNULL(NULL, '2019-05-01'); 
 Result: '2019-05-01' 
 
 SELECT ISNULL('2019-04-30', '2019-05-01'); 
 Result: '2019-04-30' 

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