int xx = ListBox1.Items.Count;
string [] elements=new string[xx];

for(int i=0;i<=xx-1;i++)
{
if (ListBox1.Items[i].Selected == true)
{
str = ListBox1.Items[i].Text;

elements[j] = str;
j = j + 1;

}
}

for (int i = 0; i <=elements.Length-1; i++)
{ 
if (i == 0)
{
str1= elements[0];
}
else if (i == 1)
{
str2 = elements[1];
}
else if (i == 2)
{ 
str3 = elements[2];
}
}
db.list1 = str1;
db.list2 = str2;
db.list3 = str3;

db.insert_MultipleSelectedItems();

grd_bind();

}
}