inserting data into database by skipping duplicate values .

Question

hai friends,

 

please let me know how to insert values into database with out repetition..  that means skipping the already entered values from datagridview..

 

 

here is my  code  

 

 

AD_ YEA R	CAT	BRANCH	REGD_ NO	STU DEN T	YEA R	GE NDE R	CAS TE
2013	A	CSE	132Z1A0501	VENU	FIRST	MALE	BCB
2013	A	CSE	132Z1A0502	NAVEEN	FIRST	MALE	BCB
2013	A	CSE	132Z1A0503	TANUSHREE	FIRST	FEMALE	BCB
2013	A	CSE	132Z1A0504	TANUSHKA	FIRST	FEMALE	BCB

  the red color indicated in the table was already entered so while updating to database these entered values should not enter again.

i am uploading excel data into datagridview. from datagridview  inserting data to database 

 

 

con.Open();

int c = dataGridView1.Rows.Count;

int d = c - 1;

MessageBox.Show(dataGridView1.Rows.Count.ToString());

try

{

if (dataGridView1.Rows.Count >= 1)

{

for (int i = 0; i <= d; i++)

{

textBox3.Text = dataGridView1.Rows[i].Cells[0].Value.ToString();//ADMIT YEAR

textBox4.Text = dataGridView1.Rows[i].Cells[1].Value.ToString();//CAT

textBox5.Text = dataGridView1.Rows[i].Cells[2].Value.ToString();//COURSE

textBox6.Text = dataGridView1.Rows[i].Cells[3].Value.ToString();//REG_NO

textBox7.Text = dataGridView1.Rows[i].Cells[4].Value.ToString();//NAME

textBox8.Text = dataGridView1.Rows[i].Cells[5].Value.ToString();//year

textBox9.Text = dataGridView1.Rows[i].Cells[6].Value.ToString();

textBox10.Text = dataGridView1.Rows[i].Cells[7].Value.ToString();

 

 

 

try

{

SqlCommand CMD = new SqlCommand("SELECT COUNT(YEAR) as Tot FROM ADD_STUDENT WHERE REGD_NO='" + textBox6.Text + "' AND YEAR='" + textBox8.Text + "' ", con);

SqlDataReader dr = CMD.ExecuteReader();

while (dr.Read())

{

int i1 = Convert.ToInt32(dr["Tot"]);

if (i1 > 0)

{

MessageBox.Show(textBox6.Text + "REGD NO ALREADY ENTERED");

}

else

{

SqlDataAdapter adapter = new SqlDataAdapter();

string sql = null;

sql = "insert into product (REGD_NO) values('"+ textBox6.Text +"')";

try

{

con.Open();

adapter.InsertCommand = new SqlCommand(sql, con );

adapter.InsertCommand.ExecuteNonQuery();

MessageBox.Show("Row inserted !! ");

con.Close();

}

catch (Exception ex)

{

MessageBox.Show(ex.ToString());

}

}

}

}// END OF TRY STATEMENT

catch (Exception ex)

{

MessageBox.Show(ex.Message, "error", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);

}

finally

{

con.Close();

}

 

 

 am getting error message like 

 

executereader requires an open and available connection. the connection's current state is open