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drizzt_xia

SqlConnection conn = new SqlConnection ("server = localhost; Initial catalog = LIS; uid = sa; password =;");
            conn.Open ();
            SqlDataAdapter adapter = new SqlDataAdapter ("SELECT XM FROM BRXX WHERE ID =" + n, conn);
            SqlCommandBuilder builder = new SqlCommandBuilder (adapter);
            
            DataSet ds = new DataSet ();
            
            string xm = Convert.ToString (ds.Tables ["BRXX"]. Rows [6] ["XM"]);

I want to get the XM value of the 6th row in the database. This is the wrong way to write it. It always contains the error "the object reference is not set to the object instance." Is there any other way to get a value in a row, or how do I do this? change?

psycholmu

SqlConnection conn = new SqlConnection ("server = localhost; Initial catalog = LIS; uid = sa; password =;");
    SqlDataAdapter adapter = new SqlDataAdapter ("SELECT XM FROM BRXX WHERE ID =" + n, conn);
    DataSet ds = new DataSet ();
    adapter.Fill (ds, "BRXX");
    string xm = ds.Tables ["BRXX"]. Rows [5] ["XM"]. ToString ();

sumu007

Write like this, there should be no data in ds,
Add adapter.Fill (ds, "BRXX"); try

yanan13115

You did not fill the data into the DataSet, of course, there will be errors, when Fill, the table structure and data are filled into the DS together! That would not be wrong!

kalian2000

Unpopulated dataset:
try ..

DataSet ds = new DataSet ();
adapter.Fill (ds, "BRXX");