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Subject:
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how to capture null value(ifpresent) from database
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Posted By:
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su
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Post Date:
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12/4/2006 10:29:36 AM
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I am using C#.NET, Visual Web Develpoper, SQL Server 2000.
In my WebForm, I am trying to get the value from database using following code : Where OSP_OrderNum is the column name in database.
// Get the value of the OSP_OrderNum field.
ordernum = (string)DataBinder.Eval(e.Item.DataItem, "OSP_OrderNum");
Here I am trying to insert the value of OSP_OrderNum into a dropdownlist of a DataGrid. Now what I would like to do is
if (ordernum == " ")
{
insert Text : "**Select Order**" into DDL
}
else
{
insert : "**Select 'ordernum**' order"
}
When I am using this loop my code breaks on the 1st line itself where I have declared ordernum. It is not able to capture null value from the database and giving me error: Unable to cast object of type 'System.DBNull' to type 'System.String'
How do I Solve this ?
Please Help!!!!
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Reply By:
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joefawcett
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Reply Date:
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12/4/2006 10:46:36 AM
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A blank space or an empty string is not the same as a NULL in a database. The error message was trying to be helpful, for once, you need to compare to System.DBNull.Value.
--
Joe (Microsoft MVP - XML)
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Reply By:
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su
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Reply Date:
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12/4/2006 11:23:01 AM
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How and where do I compare with System.DBNull.Value ?
Code does not go to if loop. Code breaks before it on the following line.
ordernum = (string)DataBinder.Eval(e.Item.DataItem, "OSP_OrderNum");
I am inserting this value in DDL of DataGrid.
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Reply By:
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joefawcett
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Reply Date:
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12/4/2006 11:58:06 AM
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Sorry, I misread where the error appeared. You need to store the value of DataBinder.Eval(e.Item.DataItem, "OSP_OrderNum") in a variable and compare to System.DBNull.Value.
--
Joe (Microsoft MVP - XML)
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Reply By:
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su
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Reply Date:
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12/4/2006 12:36:06 PM
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Hi joefawcett,
How should I compare and where as my code does not reach till if loop?
ordernum = (string)DataBinder.Eval(e.Item.DataItem, "OSP_OrderNum");
if (ordernum == System.DBNull.Value)
{
insert Text : "**Select Order**" into DDL
}
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Reply By:
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vivekshah
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Reply Date:
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12/7/2006 3:29:56 AM
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Hello Su,
In your sql query you can use
ISNULL(OSP_OrderNum,0)
The about will check if the value in OSP_OrderNum is NULL then it will replace the value with zero(0).
Hope this solves the problem you are facing
Vivek Shah
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Reply By:
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SachinMalge
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Reply Date:
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12/15/2006 8:02:30 AM
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hi, i m new member.
my problem is, i am using datagrid and in that i am showing the members information. In this information i used one field called website which is populated from database using Databinder.Eval() Method. Now i want to hide that particular control for every member whose website field is null. For displaying the website field i used the hyperlink control in template column. plz send me
some help for this asap.
thanks in advance.
Sachin
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