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();
}
}
}