Asp.net vb checking for null

Item "MyValue" until I come across a Null value. A Null value in the Database throws an exception which is easy to address with a Try Catch statement. However as mentioned in some of the excellent articles this is not a good solution for the problem. Perhaps something like: If Not Datatable.

Rows 0. Regards Martyn Fewtrell. Follow Post Reply. Martyn trying checking fo DBNull. Compare to DBNull. Thanks to both of you. Beamer " wrote: Compare to DBNull. In server side Javascript you have to test if RS "myCol". Value THEN to actually test for the value and not the object. Jeff Jeff 5 5 silver badges 12 12 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Making Agile work for data science. Stack Gives Back For example:. For comparison, the alternative code for the first of these expressions without a null-conditional operator is:.

Sometimes you need to take an action on an object that may be null, based on the value of a Boolean member on that object like the Boolean property IsAllowedFreeShipping in the following example :.

You can shorten your code and avoid manually checking for null by using the null-conditional operator as follows:. The null-conditional operators are short-circuiting. Another use for null-conditional member access is to invoke delegates in a thread-safe way with much less code.

Now, when editTransactionRow. Is there something wrong with this code? ToString and it cannot be executed. You need to check editTransactionRow. ToString ;. Edit to show you if it's not a String:. You are getting the error because a strongly-typed data set retrieves the underlying value and exposes the conversion through the property.

For instance, here is essentially what is happening:. I tried, and I make sure the above code worked. It might read terribly, but the ISIL is actually very different from IsNot Nothing, and it doesn't try and evaluate the expression, which could give a null reference exception. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How to check for a Null value in VB. NET Ask Question.

Asked 13 years ago.