いつも拝見させていただきありがとうございます。

ちょっと、変な質問で申し訳ありませんが教えてください。
フィールド名についてなんですが、今の私のつけ方に疑問
を感じまして投稿させていただきます。
環境はOS　XP-Pro　MySql4.1.13　PHP5　Apache1.3です。

以下のような感じでテーブルを作成しました。
ここで疑問ですがidはすべてidにしたのですが、それぞれ
違う名前のほうがいいのでしょうか？
たとえば、csm_id ko_id syain_idなどです。
そうした場合、他のフィールドもすべてユニークなほうが
使いやすいのでしょうか？
たとえば csm_name ko_name syain_name などです。
初歩的な質問で申し訳ありませんがよろしくお願いします。

    #customer
     $query = "CREATE TABLE " . TABLE_NAME_KOKYAKU . "("
        . "id INT NOT NULL UNIQUE PRIMARY KEY,"
        . "name VARCHAR(20),"
        . "kana VARCHAR(20),"
        . "keisho VARCHAR(6),"
        . "birthday  DATE,"
        . "ox  VARCHAR(4),"
        . "yubin VARCHAR(20),"
        . "jusho1 VARCHAR(64),"
        . "jusho2 VARCHAR(64),"
        . "tel VARCHAR(20),"
        . "fax VARCHAR(20),"
        . "keitai VARCHAR(20),"
        . "mail VARCHAR(45),"
        . "shokushu INT(2),"
        . "group_id INT,"
        . "bikou VARCHAR(256),"
        . "shoukyo  INT(1) Default 0,"
        . "modify DATETIME)";
     $result = mysql_query($query , $db);

    #子
     $query = "CREATE TABLE " . TABLE_NAME_KO . "("
            . "id INT NOT NULL UNIQUE AUTO_INCREMENT PRIMARY KEY,"
        . "name  VARCHAR(32),"
        . "kana  VARCHAR(32),"
        . "birthday  DATE,"
        . "ox  VARCHAR(4),"
        . "csm_id INT,"
        . "bikou  VARCHAR(128),"
        . "shoukyo  INT(1) Default 0,"
        . "modify DATETIME)";
     $result = mysql_query($query , $db);

    #販売履歴
     $query = "CREATE TABLE " . TABLE_NAME_HANBAI . "("
            . "id INT NOT NULL AUTO_INCREMENT UNIQUE PRIMARY KEY,"
        . "order_date DATE,"
        . "csm_id  INT,"
        . "ko_id  INT,"
        . "shohin_id INT,"
        . "shiire_tanka INT,"
        . "syanai_tanka INT,"
        . "hanbai_tanka INT,"
        . "denpyo_no INT,"
        . "nouhin DATE,"
        . "shoukyo  INT(1) Default 0,"
        . "modify DATETIME)";
     $result = mysql_query($query , $db);

    #フォロー履歴
     $query = "CREATE TABLE " . TABLE_NAME_FOLLOW . "("
            . "id INT NOT NULL AUTO_INCREMENT UNIQUE PRIMARY KEY,"
        . "follow_date DATE,"
        . "csm_id  INT,"
        . "tanto_id  INT,"
        . "shubetsu_id INT,"
        . "naiyou VARCHAR(200),"
        . "bikou VARCHAR(32),"
        . "shoukyo  INT(1) Default 0,"
        . "modify DATETIME)";
     $result = mysql_query($query , $db);

    #フォロー種別
     $query = "CREATE TABLE " . TABLE_NAME_FOLLOW_SHUBETSU . "("
        . "id INT NOT NULL UNIQUE PRIMARY KEY,"
        . "name  VARCHAR(50),"
        . "hosoku  VARCHAR(20),"
        . "bikou  VARCHAR(50),"
        . "shoukyo  INT(1) Default 0,"
        . "modify DATETIME)";
     $result = mysql_query($query , $db);

以下省略-----