In this Post Excel Data save to SQL Server ,
creating UserDefined Function and Button Click Event

Important NameSpaces Used
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using System.Data;
using System.Data.SqlClient;
using System.IO;
using System.Data.OleDb;
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Upload / Save To SQL Server Button Click Event Coding
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int rollno;
        String sname;
        String fname;
        String mname;
        string path = Path.GetFileName(FileUpload1.FileName);
        path = path.Replace(" ", "");
        FileUpload1.SaveAs(Server.MapPath("~/ExcelFile/") + path);
        String ExcelPath = Server.MapPath("~/ExcelFile/") + path;
        OleDbConnection mycon = new OleDbConnection("Provider = Microsoft.ACE.OLEDB.12.0; Data Source = " + ExcelPath + "; Extended Properties=Excel 8.0; Persist Security Info = False");
        mycon.Open();
        OleDbCommand cmd = new OleDbCommand("select * from [Sheet1$]", mycon);
        OleDbDataReader dr = cmd.ExecuteReader();
        while(dr.Read())
        {
            // Response.Write("<br/>"+dr[0].ToString());
            rollno = Convert.ToInt32(dr[0].ToString());
            sname = dr[1].ToString();
            fname = dr[2].ToString();
            mname = dr[3].ToString();
            savedata(rollno, sname, fname, mname);


        }
        Label3.Text = "Data Has Been Saved Successfully";

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UserDefined Function Coding ( SaveData )
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 private void savedata(int rollno1,String sname1,String fname1,String mname1)
    {
        String query = "insert into studentdetail(rollno,sname,fathername,mothername) values(" + rollno1 + ",'" + sname1 + "','" + fname1 + "','" + mname1 + "')";
        String mycon = "Data Source=sk-pc; Initial Catalog=ExcelDatabase; Integrated Security=true";
        SqlConnection con = new SqlConnection(mycon);
        con.Open();
        SqlCommand cmd = new SqlCommand();
        cmd.CommandText = query;
        cmd.Connection = con;
        cmd.ExecuteNonQuery();
    }