SQL isnull () function

SQL isnull () function

Replace null with the specified replacement value.
Syntax
Isnull (check_expression, replacement_value)
Parameters
Check_expression
Whether the expression is null is checked. Check_expression can be of any type.
Replacement_value
The expression returned when check_expression is null. Replacement_value must be of the same type as check_expresssion.
Return type
Returns the same type as check_expression.
Note
If check_expression is not null, the value of this expression is returned; otherwise, the value of replacement_value is returned.
If the field type is varchar and the value is ''or null, the return value is replacement_value.
If the field type is int and the value is 0 or null, the return value is replacement_value.

The following example shows how to select the title, type, and price for all books in the titles table. If the price for a title is null, the price displayed in the result set is 0.00.
Use pubs
Go
Select substring (title, 1, 15) as title, type as type,
Isnull (price, 0.00) as price
From titles
Go
The following is the result set:

Title Type Price
-----------------------------------------------------
The busy execut business 19.99
Cooking with Co Business 11.95
You can combat business 2.99
Straight talk a business 19.99
Silicon Valley mod_cook 19.99
The Gourmet mic mod_cook 2.99
The psychology undecided 0.00
But is it user popular_comp 22.95
Secrets of sili popular_comp 20.00
Net etiquette popular_comp 0.00
PC phobic psychology 21.59
Is anger the en psychology 10.95
Life without Fe fig 7.00
Prolonged data psychology 19.99
Emotional secur psychology 7.99
Onions, leeks, trad_cook 20.95
Policty years in trad_cook 11.95
Sushi, anyone? Trad_cook 14.99