Get min, max and avg records from a database using SQL

This code snippet shows how to select minimum, maximum, and average values from a database using SQL statements.

Get min, max and avg records from a database using SQL 

I have a Student table in a database and that has smarks column. We can use SQL Min, Max and Avg functions to get minimum, maximum, and average values. I am using OleDb data provider to connect to the database. 

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.OleDb;

namespace Display_min_max_avg_records_in_textbox

{

    public partial class Form1 : Form

    {

        string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["dsn"];

        OleDbCommand com;

        OleDbDataAdapter oledbda;

        DataSet ds = new DataSet();

        string str;

      

      

        public Form1()

        {

            InitializeComponent();

        }

 

        private void Form1_Load(object sender, EventArgs e)

        {

            OleDbConnection con = new OleDbConnection(ConnectionString);

            con.Open();

            str = "select * from student";

            com = new OleDbCommand(str, con);

            oledbda = new OleDbDataAdapter(com);

            ds = new DataSet();

            oledbda.Fill(ds, "student");

            dataGridView1.DataSource = ds;

            dataGridView1.DataMember = "student";

            con.Close();

 

 

        }

 

        private void button1_Click(object sender, EventArgs e)

        {

            OleDbConnection con = new OleDbConnection(ConnectionString);

            con.Open();

            str = "select max(smarks)from student";

            com = new OleDbCommand(str, con);

            textBox1.Text = com.ExecuteScalar().ToString();

            con.Close();

 

        }

 

        private void button2_Click(object sender, EventArgs e)

        {

            OleDbConnection con = new OleDbConnection(ConnectionString);

            con.Open();

            str = "select min(smarks)from student";

            com = new OleDbCommand(str, con);

            textBox2.Text = com.ExecuteScalar().ToString();

            con.Close();

 

        }

 

        private void button3_Click(object sender, EventArgs e)

        {

            OleDbConnection con = new OleDbConnection(ConnectionString);

            con.Open();

            str = "select avg(smarks)from student";

            com = new OleDbCommand(str, con);

            textBox3.Text = com.ExecuteScalar().ToString();

            con.Close();

 

        }

    }

}