获取错误对象引用未设置为对象的实例

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

我正在尝试将数据从sql表“checkin”复制到文本框中的表单上自动填充..单击按钮

DataSet ds = null;

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

3 个解决方案

#1

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.

ds从null开始，并且您不会显示任何使ds不是null的代码。因此，ds.Tables [0]确实会爆发NullReferenceException。

Make ds something non-null.

使ds非空。

#2

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

在将其设置为对象之前，您无法使用ds ....

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

因此，此调用无效ds.Tables [0]; - >当ds为null时，您正尝试从ds访问表

#3

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

像其他人一样，你需要先实例化ds才能使用它。

DataSet ds = new DataSet();

#1