How C # merges two database tables

Table 1.tb_1 Table 2.tb_2

Merging tables 1 and 2

Code:

public partial class Form1:form
{
Public Form1 ()
{
InitializeComponent ();
}
SqlConnection Conn;
private void Form1_Load (object sender, EventArgs e)
{
conn = new SqlConnection ("server=.; database=k;uid=sa;pwd=123456 ");
DataSet ds = new DataSet ();
DataSet ds1 = new DataSet ();
SqlDataAdapter SDA = new SqlDataAdapter ("select * from Tb_1", conn);
Sda. Fill (DS);
SqlDataAdapter sda1 = new SqlDataAdapter ("select * from tb_2", conn);
SqlCommandBuilder SBL = new SqlCommandBuilder (SDA1);
Sda1. Fill (DS1);
DS1. Merge (Ds,true,missingschemaaction.addwithkey);
Datagridview1.datasource = DS1. Tables[0];
}

How C # merges two database tables