Enter null value when text box is empty

Question

1.00/5 (1 vote)

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I have tried different method to do this but none is working:

<pre lang="c#">
string strListOthLog = ((TextBox)fvAddBookingInfo.FindControl("txtOtherLogList")).Text;
string strComment = ((TextBox)fvAddBookingInfo.FindControl("txtComment")).Text;
.......
 cmd.Parameters.Add("@other_logon_list", SqlDbType.NVarChar).Value = string.IsNullOrEmpty(strListOthLog) ? (object)DBNull.Value : strListOthLog;
   
if (string.IsNullOrEmpty(strComment))
            {
                cmd.Parameters.Add("@additional_comments", SqlDbType.NVarChar).Value = System.DBNull.Value;
            }
            else
            {
                cmd.Parameters.Add("@additional_comments", SqlDbType.NVarChar).Value = strComment;
            }

What I have tried:

System.DBNull.Value in different ways.

Posted 18-Aug-16 5:30am

Member 12671834

Updated 26-Aug-16 2:40am

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Comments

Maciej Los 18-Aug-16 12:17pm

"Not working" is not informative at all!
What's your issue? What's wrong wiht above code? What kind of error do you get?

Member 12671834 18-Aug-16 12:25pm

I don't get any error but it does not enter null in the database, it enter blank.

Karthik_Mahalingam 18-Aug-16 12:26pm

try passing 'null' value

Maciej Los 18-Aug-16 16:56pm

Does the database accept null values for that field? Why to add comment if its connent is null?!? Illogical...

Bernhard Hiller 19-Aug-16 4:07am

HOW do you see that it is "blank" instead of "null"? What's your editor/viewer?

Member 12671834 18-Aug-16 12:54pm

That is what I am trying to do but it is entering blank, not null. Can you please let me know what is wrong in my code or how to pass null value?
Thanks,

4 solutions

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Karthik_Mahalingam · Answer 1 · 2016-08-18T17:58:00

use null instead of DBNull.Value

C#

cmd.Parameters.Add("@other_logon_list", SqlDbType.NVarChar).Value = string.IsNullOrWhiteSpace(strListOthLog) ? null : strListOthLog;
cmd.Parameters.Add("@additional_comments", SqlDbType.NVarChar).Value = string.IsNullOrWhiteSpace(strComment) ? null : strComment;

DBNull.Value:
DBNull.Value is for the purpose of working with databases. A database column can contain a null value. However, when that data is selected into an object (such as a DataTable) in code, there is an object there to reference as far as the code is concerned. However, that object contains a representation of a null value from the database. Thus, DBNull.Value exists to represent that distinction. It basically means "There is a C# object here which grabbed a value from a database, but that value is null."

refer null vs DBNull.Value[^]

ZurdoDev · Answer 2 · 2016-08-18T10:13:00

Solution 1

This code will work

C#

if (strListOthLog == "")
  cmd.Parameters.AddWithValue("@other_logon_list", DBNull.Value);
else
  cmd.Parameters.AddWithValue("@other_logon_list", strListOthLog);

Posted 18-Aug-16 10:13am

ZurdoDev

Comments

Maciej Los 18-Aug-16 17:10pm

Well...
Of course, this should work as well, but - in my opinion - that does not resolve OP's issue. Please, read my comment to the OP's comment. Mayby i'm wrong, but is there any sense to insert useless data to the database? ;)

ZurdoDev 18-Aug-16 19:55pm

I don't understand your comment.

Member 12671834 19-Aug-16 11:37am

@RyanDev: I tried but this didn't work. Thanks for trying to help.

ZurdoDev 19-Aug-16 11:38am

It does work, so please explain what you mean by "this didn't work."

Member 12671834 · Answer 3 · 2016-08-26T02:40:00

I thank you all for helping me. I tried all the above mentioned ways one at a time and was not successful entering null value instead of blank empty space in a table. Finally I got it worked by doing the following:
In the stored procedure I set the default value null for the fields that are not required (user may choose not to enter a value).
@additional_comments varchar (500) = null
Then in the lbInsert_Click event I have following:
string strComment = ((TextBox)fvAddBookingInfo.FindControl("txtComment")).Text;
....
if (strComment != String.Empty)
{
cmd.Parameters.Add("@additional_comments", SqlDbType.VarChar).Value = strComment;
}
This is working for me.
Thanks again to all of you for your support.

manishbg · Answer 4 · 2016-08-18T20:32:00

Solution 3

you change in db set column accept null also.

if(txtval=="")
{
val=" ";

}
else
{
val=txtval;

}

Posted 18-Aug-16 20:32pm

manishbg