Vba textbox null value

For controls, you can set the ValidationRule property to any valid expression. For field and record validation rules, the expression can't contain user-defined functions, domain aggregate or aggregate functions, the Eval function, the CurrentUser method, or references to forms, queries, or tables.

In addition, field validation rules can't contain references to other fields. For records, expressions can include references to fields in that table. Microsoft Access automatically validates values based on a field's data type; for example, Access doesn't allow text in a numeric field. You can set rules that are more specific by using the ValidationRule property. If you set the ValidationRule property but not the ValidationText property, Access displays a standard error message when the validation rule is violated.

If you set the ValidationText property, the text that you enter is displayed as the error message. For example, when a record is added for a new employee, you can enter a ValidationRule property requiring that the value in the employee's StartDate field fall between the company's founding date and the current date. If the date entered isn't in this range, you can display the ValidationText property message: "Start date is incorrect. If you create a control by dragging a field from the field list, the field's validation rule remains in effect, although it isn't displayed in the control's ValidationRule property box on the property sheet.

This is because a field's validation rule is inherited by a control bound to that field. Validation rules that you set for fields and controls are applied when you edit the data and the focus leaves the field or control.

If you create validation rules for both a field and a control bound to the field, both validation rules are applied when you edit data and the focus leaves the control.

An object variable is considered nothing if its reference count is zero. For such variables, objPtr returns 0. An object can be tested for nothingness with the is nothing construct:.

The opposite is possible with not obj is nothing not with obj is not nothing :. Also, the function typeName obj returns the string "Nothing" if obj is nothing. Thus, empty signals that the variable is not initialized. This function can be used in any subprocedure and function procedure. You are free to use this image on your website, templates etc, Please provide us with an attribution link How to Provide Attribution? The below code is the demonstration code for you.

Now check whether the empty value is NULL or not. Below code is to test whether the empty string is NULL or not.