Description:
Judge if the value of a parameter is null.
Syntax:
isnull(Exp)
Note:
The function judges whether parameter Exp is a null value.
Parameter:
|
Exp |
An expression of any data type. |
Return value:
Boolean
Example:
|
isnull ("") |
false |
|
isnull (1234) |
false |
|
isnull (null) |
true |
|
isnull (null+1) |
The result is determined by whether you check option “Null Control” or not. The expression returns true if the option is checked; and false if the option isn’t checked. |