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The IsNull () function checks whether an expression contains Null (no data). This function returns a Boolean value. TRUE (-1) indicates that the expression is a Null value, and FALSE (0) indicates that the expression is not a Null value.
28 lut 2017 · If you want to check if a string is the empty string, you use. if (s.equals("")) or. if (s.length() == 0) or. if (s.isEmpty()) An empty string is an empty string. It's not null. And == must never be used to compare string contents. == tests if two variables refere to the same object instance.
For example, you can use this function to convert a Null value to another value and prevent it from propagating through an expression. Or you can use: IIF(IsNull(MaritalStatus),"SINGLE",MaritalStatus)
The Microsoft Access IsNull function returns TRUE if the expression is a null value. Otherwise, it returns FALSE. Syntax. The syntax for the IsNull function in MS Access is: IsNull ( expression ) Parameters or Arguments. expression. A variant that contains a string or numeric value. Returns.
The IsNull() function checks whether an expression contains Null (no data). This function returns a Boolean value. TRUE (-1) indicates that the expression is a Null value, and FALSE (0) indicates that the expression is not a Null value.
SELECT ProductID, isNull(Discount) AS NullStatus FROM ProductSales; Returns values from the field "ProductID", evaluates if the values in the field "Discount" are Null, returns -1 (True) and 0 (False) in column NullStatus.
23 lis 2015 · You must use IsNull(value) or Not Isnull(value) if you want to know if something is null. As an alternative method or to cover more bases you can use nz(VariableName) which returns a zero length string "" (which is also the same as vbNullString ) if VariableName is null.
