-Esta mas claro asi no?
Código PHP:
$link=mysql_connect("localhost","root","") or die (mysql_error());
mysql_select_db("checkbox",$link) or die (mysql_error());
$parte1 ="bal bla blaal ".$variable." kdfkjsdfdslfk ".variabe2."jnsdad ".$result['variable_para_consulta1']."blablabla";
if($_POST['parte1'] != ""){
$parte1 ="bal bla blaal ".$variable." kdfkjsdfdslfk ".variabe2."jnsdad ".$result['variable_para_consulta1']."blablabla";
$sql_parte1 = "insert into tabla_checkbox (parte1) values ('$parte1')";
mysql_query($sql_parte1)or die (mysql_error());
echo" se envio a parte 1";
}else{
echo "no se envio";
};