using System;
using System.Data.SqlClient;
class Program
{
static void Main()
{
string connectionString ="your connection string";
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
using (SqlCommand command = new SqlCommand("SELECT classify21.Age, classify21.workclass, classify21.fnlwgt, classify22.maritalstatus, classify23.educationnum FROM classify21 INNER JOIN classify22 on classify21.workclass=classify22.workclass INNER JOIN classify23 on classify22.workclass = classify23.workclass", connection))
{
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
GridView1.DataSource=reader;
GridView1.DataBind();
}
}
}
}
}