現在書いているPHPのコードはこのような感じです。

$sql1 = "SELECT x FROM tableA";
$sql2 = "SELECT x FROM tableB";
$tablea = mysql_query($sql1);
$tableb = mysql_query($sql2);

while($row = mysql_fetch_array($tablea)){
echo $row['data_id'] ;
echo $row['info'] ;
echo $row['date'] ;
echo $row['sonota'] ;
}

while ($row2 = mysql_fetch_array($tableb)){
if ($row2['data_id'] eq $row['data_id']){
echo $row2['koshin_joho'];
}
}