using System;
 using System.Data;
 using System.Data.SqlClient;
 
 class SqlCommandexample
 {
     SqlConnection conn;
 
     public SqlCommandDemo()
     {
         // Instantiate the connection
         conn = new SqlConnection(
            "Data Source=computer;Initial Catalog=Emp;Integrated Security=SSPI");
     }
 
     // call methods that demo SqlCommand capabilities
     static void Main()
     {
         SqlCommandexample scd = new SqlCommandexampleo();
 
         Console.WriteLine();
         Console.WriteLine("Categories Before Insert");
         Console.WriteLine("------------------------");
 
         // use ExecuteReader method
         scd.ReadData();
 
         // use ExecuteNonQuery method for Insert
         scd.Insertdata();
         Console.WriteLine();
         Console.WriteLine("Categories After Insert");
         Console.WriteLine("------------------------------");
 
        scd.ReadData();
 
         // use ExecuteNonQuery method for Update
         scd.UpdateData();
 
         Console.WriteLine();
         Console.WriteLine("Categories After Update");
         Console.WriteLine("------------------------------");
 
         scd.ReadData();
 
         // use ExecuteNonQuery method for Delete
         scd.DeleteData();
 
         Console.WriteLine();
         Console.WriteLine("Categories After Delete");
         Console.WriteLine("------------------------------");
 
         scd.ReadData();
 
         // use ExecuteScalar method
         int numberOfRecords = scd.GetNumberOfRecords();
 
         Console.WriteLine();
         Console.WriteLine("Number of Records: {0}", numberOfRecords);
     }
 
     /// <summary>
     /// use ExecuteReader method
     /// </summary>
     public void ReadData()
     {
        SqlDataReader rdr = null;
 
         try
         {
             // Open the connection
             conn.Open();
 
             // 1. Instantiate a new command with a query and connection
             SqlCommand cmd = new SqlCommand("select EmpName from Emp", conn);
 
             // 2. Call Execute reader to get query results
             rdr = cmd.ExecuteReader();
 
             // print the CategoryName of each record
             while (rdr.Read())
             {
                 Console.WriteLine(rdr[0]);
             }
         }
         finally
         {
             // close the reader
             if (rdr != null)
             {
                 rdr.Close();
             }
 
             // Close the connection
             if (conn != null)
             {
                 conn.Close();
             }
         }
     }
 
     /// <summary>
     /// use ExecuteNonQuery method for Insert
     /// </summary>
     public void Insertdata()
     {
         try
         {
             // Open the connection
             conn.Open();
 
             // prepare command string
             string insertString = @"
                 insert into Emp
                 (EmpName, post)
                 values ('Raj', 'A\c')";
 
             // 1. Instantiate a new command with a query and connection
             SqlCommand cmd = new SqlCommand(insertString, conn);
 
             // 2. Call ExecuteNonQuery to send command
             cmd.ExecuteNonQuery();
         }
         finally
         {
             // Close the connection
             if (conn != null)
             {
                 conn.Close();
             }
         }
     }
 
     /// <summary>
     /// use ExecuteNonQuery method for Update
     /// </summary>
     public void UpdateData()
     {
         try
         {
             // Open the connection
             conn.Open();
 
             // prepare command string
             string updateString = @"
                 updateEmp
                 set EmpName = 'Anil'
                 where EmpName = 'Raj'";
 
             // 1. Instantiate a new command with command text only
             SqlCommand cmd = new SqlCommand(updateString);
 
             // 2. Set the Connection property
             cmd.Connection = conn;
 
             // 3. Call ExecuteNonQuery to send command
             cmd.ExecuteNonQuery();
        }
         finally
         {
             // Close the connection
             if (conn != null)
             {
                 conn.Close();
             }
         }
     }
 
     /// <summary>
     /// use ExecuteNonQuery method for Delete
     /// </summary>
     public void DeleteData()
     {
         try
         {
             // Open the connection
             conn.Open();
 
             // prepare command string
             string deleteString = @"
                 delete from Emp
                 where EmpName = 'Ashish'";
 
             // 1. Instantiate a new command
             SqlCommand cmd = new SqlCommand();
 
             // 2. Set the CommandText property
             cmd.CommandText = deleteString;
 
             // 3. Set the Connection property
             cmd.Connection = conn;
 
             // 4. Call ExecuteNonQuery to send command
             cmd.ExecuteNonQuery();
         }
         finally
         {
             // Close the connection
             if (conn != null)
             {
                 conn.Close();
             }
         }
     }
 
     /// <summary>
     /// use ExecuteScalar method
     /// </summary>
     /// <returns>number of records</returns>
     public int GetNumberOfRecords()
     {
         int count = -1;
 
         try
         {
             // Open the connection
             conn.Open();
 
             // 1. Instantiate a new command
             SqlCommand cmd = new SqlCommand("select count(*) from Emp", conn);
 
             // 2. Call ExecuteScalar to send command
             count = (int)cmd.ExecuteScalar();
         }
         finally
         {
            // Close the connection
             if (conn != null)
             {
                 conn.Close();
             }
         }
         return count;
     }
 }