Okay,First of all let me introduce myself as newbee to this language.
this is my third day with program,I usually Practice at college where Visual studio 2010 is installed.
I have VS2012 ultimate.
If I sound silly forgive me,but I am really desperate here.
1st Problem,I couldnt create New SQL server database,so I added a newone with name database.mdf.
2nd I ceated a table and so on...now lets come to the code I have written.
Also I forgot to mention that same code works great with VS 2010 at my college PC.
Now I am confused.
error "Object reference not set to an instance of an object." at Form1_Load..I have mention in code too.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
SqlConnection con;
SqlCommand cmd;
SqlDataAdapter sda;
SqlDataReader sdr;
DataSet ds;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
string st = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;//Object reference not set to an instance of an object.
con = new SqlConnection(st);
fill();
}
public void fill()
{
if (con.State != ConnectionState.Open)
{
con.Open();
}
string qry = "Select *from Table";
cmd = new SqlCommand(qry, con);
sda = new SqlDataAdapter(cmd);
ds = new DataSet();
sda.Fill(ds);
ds.Tables[0].TableName = "abc";
dataGridView1.DataSource = ds.Tables["abc"];
}
private void btn_Save_Click(object sender, EventArgs e)
{
string qry = "INSERT INTO Table(Name,Roll,Grade)Values('" + textBox1.Text + "', '" + textBox2.Text + "', '" + textBox3.Text + "')";
cmd = new SqlCommand(qry, con);
cmd.ExecuteNonQuery();
fill();
textBox1.Text = "";
textBox2.Text = "";
textBox3.Text = "";
}
private void btn_Delete_Click(object sender, EventArgs e)
{
string qry = "DELETE FROM Table WHERE Name='" + textBox1.Text + "'";
cmd = new SqlCommand(qry, con);
cmd.ExecuteNonQuery();
fill();
MessageBox.Show("File Deleted");
textBox1.Text = "";
textBox2.Text = "";
textBox3.Text = "";
}
private void btn_update_Click(object sender, EventArgs e)
{
string qry = "Update Table set Name = '" + textBox1.Text + "',Grade = '" + textBox3.Text + "' where Roll = '" + textBox2.Text + "'";
cmd = new SqlCommand(qry, con);
cmd.ExecuteNonQuery();
fill();
textBox1.Text = "";
textBox2.Text = "";
textBox3.Text = "";
}
private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
}
}
}
