how to set object item to null in vb.net

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hi all ,
i have radio button
with 2 values 1,0 yes or no
if user choose no
i have to object elments their values should be null
one of them is datetime
rational_obj.OfficeWorkApproveDate =nothing
and the other one is string
how can i put them to null in vb.net
?

Posted 26-Oct-14 6:40am

fady_hasnaa

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Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 26-Oct-14 12:54pm

Not clear. What is the issue?

1 solution

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Thomas Daniels · Answer 1 · 2014-10-26T06:53:00

Solution 1

If it's a string, you can just set it to Nothing, because String is a reference type.

VB.NET

yourString = Nothing

But for a value type (and DateTime is one), Nothing gives it the equivalent to default(T) in C#, and for DateTime, this is DateTime.MinValue. If you want to set it to Nothing, make OfficeWorkApproveDate a nullable type[^] (so when you create the variable, add a question mark after the variable name).
Then you can give it the Nothing value:

VB.NET

rational_obj.OfficeWorkApproveDate = Nothing

And later, if you want to test whether it has a value, try this:

VB.NET

If rational_obj.OfficeWorkApproveDate.HasValue Then
    Dim approveDate As DateTime = rational_obj.OfficeWordApproveDate.Value
    ' do operations with approveDate
Else
    ' it does not have a value
End If

Posted 26-Oct-14 6:53am

Thomas Daniels

Updated 26-Oct-14 6:54am

v2

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fady_hasnaa 26-Oct-14 16:14pm

when puting rational_obj.OfficeWordApproveDate=DateTime.MinValue
in inserting to db it will be like this
INSERT INTO RationaleSystemicTbl
(SchID ,InsuranceOrderNO, InsuranceEDate, InsuranceNoOfSubscribeSToutorial, InsuranceNoOfSubscribeNSToutorial,InsuranceNoOfSubscribeSAdimistrator, InsuranceNoOfSubscribeNSAdimistrator, InsuranceNoOfSubscribeSUsers, InsuranceNoOfSubscribeNSUsers, JoinFilledSchoolDate, AmanahApprove, AmanaApproveDate, FileNoInOfficeWork, OfficeWorkApprove, AlzakahEDate, OfficeWorkApproveDate, TaesheeratTotal, TaesheeratUse, TaesheeratUnUse,Amanah_approve_num,Office_work_approve_num,non_sa_on_kfalah)
VALUES(N'1988',3249423,CONVERT(VARCHAR(10),'10/8/2014', 111) , 16, 16, 19,7, 18, 18, CONVERT(VARCHAR(10),'9/25/2014', 111) , 0, CONVERT(VARCHAR(10),'12:00:00 AM', 111) , 03293232,null , CONVERT(VARCHAR(10),'10/29/2014', 111) , CONVERT(VARCHAR(10),'12:00:00 ', 111) ,null , 17, 16, 14,null,17)
---------------
CONVERT(VARCHAR(10),'12:00:00 ', 111) and the column is datetime will not accept string how can i fix it ?
as i can not put it to nullable as sometimes it has value

Thomas Daniels 27-Oct-14 3:29am

Use the if-else statement I provided in my answer, and if your nullable has a value, put that value in your SQL query, and if it does not have a value, put null in your SQL query (SQL supports null for datetime).