Getting error Object reference not set to an instance of an object

Question

I'm trying to copy the data from sql table "checkin " to auto fill in on a form in a textbox .. on a button click

DataSet ds = null;

private void button8_Click(object sender, EventArgs e)
{
    tblNamesBS.DataSource = ds.Tables[0];
     textBox2.DataBindings.Add(new Binding("Text", tblNamesBS,"GuestName"));
}

Let me see throught my Crystal Ball and find the solution for your question. Ahhh ... wait I got it: ds is null. — Johannes Wanzek
– Johannes Wanzek, Commented May 31, 2013 at 12:17
@inxs Your Crystal Ball must be newer than mine, I can't even work out the question. — VisualMelon
– VisualMelon, Commented May 31, 2013 at 12:26

Marc Gravell · Accepted Answer · 2013-05-31 12:16:42Z

3

ds starts off as null, and you show no code that would make ds anything other than null. Thus indeed, ds.Tables[0] will explode with a NullReferenceException.

Make ds something non-null.

answered May 31, 2013 at 12:16

Marc Gravell

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6 Comments

user2430070 Over a year ago

thats wat i want to know how to make it non null :P

Marc Gravell Over a year ago

@user2430070 what have you tried? what do you want it to contain?

user2430070 Over a year ago

tblNamesBS.DataSource = ds.Tables[0] i want to put a table name "CheckIn" .. at ds.Tables[0] like dis ds.tables[CheckIn] .. but its showing an error 'Hotel_Essencia.CheckIn' is a 'type' but is used like a 'variable'

Johannes Wanzek Over a year ago

You should do a C# and .NET Tutorial first. No offense but this is a QA forum and no C# Beginner course.

Marc Gravell Over a year ago

@user2430070 I kinda have to agree with inxs here - there are a million and twenty "how to do data access" resources on the web; and personally I would say "the first step is: don't use DataSet"

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Gaston Claret · Accepted Answer · 2013-05-31 12:17:51Z

2

You cant use ds before setting it to an object....

Therefore, this call is invalid ds.Tables[0]; -> You are trying to acces Tables from ds, when ds is null

answered May 31, 2013 at 12:17

Gaston Claret

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Comments

officert · Accepted Answer · 2013-05-31 12:20:23Z

0

Like the other guys said you need to instantiate ds before you can use it.

DataSet ds = new DataSet();

answered May 31, 2013 at 12:20

officert

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