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Join Date: Sep 2007
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Junior Poster in Training
How do I Evaluate Null value from database? I have been looking for a way to evaluate if a column in a database has a null value in it. So far, every method suggested have failed and I would like to know anyone else have successfully evaluate a null value in C# Visual Studio 2005.
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Join Date: Feb 2008
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Light Poster
you can use nullable types i.e. - int? myVar = ... ;
you can also check to see if the value is = to System.DbNull...
you can also check to see if the value is = to System.DbNull...
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Join Date: Sep 2007
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Junior Poster in Training
How exactly do I do that, I've use IsDBNull, Convert.IsDBNull, IsDBNull.Value and nothing works and I've tried type casting. ????
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Join Date: Mar 2008
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Newbie Poster
The following can help you but i am sure whether this is the right way.
While selecting the column check for null values like
select ISNULL(class,-1) from student
If the column class contains null values,the query returns -1 value.
Using this value you can identity the column contains null value.
Good Luck.
While selecting the column check for null values like
select ISNULL(class,-1) from student
If the column class contains null values,the query returns -1 value.
Using this value you can identity the column contains null value.
Good Luck.
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Join Date: Feb 2005
Location: Braintree, UK
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You need to compare the column value with System.DBNull.Value
So assuming a DataTable for example:
So assuming a DataTable for example:
if( myDataTable.Rows[0]["someColumn"].Equals(System.DBNull.Value) )
{
//Handle situation for null value.
} Last edited by hollystyles : Mar 14th, 2008 at 4:59 am.
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Join Date: Sep 2007
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Junior Poster in Training
I tried that method already and it does not work.
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Join Date: Feb 2005
Location: Braintree, UK
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Hmm... well it works for me. You'll have to post some code or give more information.
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Join Date: Dec 2007
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Posting Whiz in Training
you can also get the value of the cell and use .text.tostring
then test the length of the string len(abc) > 0
then test the length of the string len(abc) > 0
--
"Dummy."
"Dummy."
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Join Date: Sep 2007
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Junior Poster in Training
Here is the code
[WebMethod]
public int TestDBNullValue(string PID)
{
int ErrorValue = 0;
if (PID.Equals(String.Empty))
{
ErrorValue = 10110; //PID is null or empty
}
else
{
DeviceTableAdapter DeviceAdapter = new DeviceTableAdapter();
JeanPierre.DeviceDataTable DeviceTable = DeviceAdapter.GetDeviceUIDByPID(PID);
if (DeviceTable.Count.Equals(0))
{
ErrorValue = 1111; //No device found
}
else
{
JeanPierre.DeviceRow DevRows = DeviceTable[0];
if(DevRows.TrackingMode.Equals(System.DBNull.Value))
{
ErrorValue = 1;
}
else
{
ErrorValue = 41;
}
}
}
return (ErrorValue);
} |
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