MySQLにてカタカナをひらがなに一括置換

UPDATE table_name SET column_name = REPLACE(column_name, "ア", "あ");
UPDATE table_name SET column_name = REPLACE(column_name, "イ", "い");
UPDATE table_name SET column_name = REPLACE(column_name, "ウ", "う");
UPDATE table_name SET column_name = REPLACE(column_name, "エ", "え");
UPDATE table_name SET column_name = REPLACE(column_name, "オ", "お");

UPDATE table_name SET column_name = REPLACE(column_name, "ァ", "ぁ");
UPDATE table_name SET column_name = REPLACE(column_name, "ィ", "ぃ");
UPDATE table_name SET column_name = REPLACE(column_name, "ゥ", "ぅ");
UPDATE table_name SET column_name = REPLACE(column_name, "ェ", "ぇ");
UPDATE table_name SET column_name = REPLACE(column_name, "ォ", "ぉ");

UPDATE table_name SET column_name = REPLACE(column_name, "カ", "か");
UPDATE table_name SET column_name = REPLACE(column_name, "キ", "き");
UPDATE table_name SET column_name = REPLACE(column_name, "ク", "く");
UPDATE table_name SET column_name = REPLACE(column_name, "ケ", "け");
UPDATE table_name SET column_name = REPLACE(column_name, "コ", "こ");

UPDATE table_name SET column_name = REPLACE(column_name, "ガ", "が");
UPDATE table_name SET column_name = REPLACE(column_name, "ギ", "ぎ");
UPDATE table_name SET column_name = REPLACE(column_name, "グ", "ぐ");
UPDATE table_name SET column_name = REPLACE(column_name, "ゲ", "げ");
UPDATE table_name SET column_name = REPLACE(column_name, "ゴ", "ご");

UPDATE table_name SET column_name = REPLACE(column_name, "サ", "さ");
UPDATE table_name SET column_name = REPLACE(column_name, "シ", "し");
UPDATE table_name SET column_name = REPLACE(column_name, "ス", "す");
UPDATE table_name SET column_name = REPLACE(column_name, "セ", "せ");
UPDATE table_name SET column_name = REPLACE(column_name, "ソ", "そ");

UPDATE table_name SET column_name = REPLACE(column_name, "ザ", "ざ");
UPDATE table_name SET column_name = REPLACE(column_name, "ジ", "じ");
UPDATE table_name SET column_name = REPLACE(column_name, "ズ", "ず");
UPDATE table_name SET column_name = REPLACE(column_name, "ゼ", "ぜ");
UPDATE table_name SET column_name = REPLACE(column_name, "ゾ", "ぞ");

UPDATE table_name SET column_name = REPLACE(column_name, "タ", "た");
UPDATE table_name SET column_name = REPLACE(column_name, "チ", "ち");
UPDATE table_name SET column_name = REPLACE(column_name, "ツ", "つ");
UPDATE table_name SET column_name = REPLACE(column_name, "テ", "て");
UPDATE table_name SET column_name = REPLACE(column_name, "ト", "と");
UPDATE table_name SET column_name = REPLACE(column_name, "ッ", "っ");

UPDATE table_name SET column_name = REPLACE(column_name, "ダ", "だ");
UPDATE table_name SET column_name = REPLACE(column_name, "ヂ", "ぢ");
UPDATE table_name SET column_name = REPLACE(column_name, "ヅ", "づ");
UPDATE table_name SET column_name = REPLACE(column_name, "デ", "で");
UPDATE table_name SET column_name = REPLACE(column_name, "ド", "ど");


UPDATE table_name SET column_name = REPLACE(column_name, "ナ", "な");
UPDATE table_name SET column_name = REPLACE(column_name, "ニ", "に");
UPDATE table_name SET column_name = REPLACE(column_name, "ヌ", "ぬ");
UPDATE table_name SET column_name = REPLACE(column_name, "ネ", "ね");
UPDATE table_name SET column_name = REPLACE(column_name, "ノ", "の");

UPDATE table_name SET column_name = REPLACE(column_name, "ハ", "は");
UPDATE table_name SET column_name = REPLACE(column_name, "ヒ", "ひ");
UPDATE table_name SET column_name = REPLACE(column_name, "フ", "ふ");
UPDATE table_name SET column_name = REPLACE(column_name, "ヘ", "へ");
UPDATE table_name SET column_name = REPLACE(column_name, "ホ", "ほ");

UPDATE table_name SET column_name = REPLACE(column_name, "バ", "ば");
UPDATE table_name SET column_name = REPLACE(column_name, "ビ", "び");
UPDATE table_name SET column_name = REPLACE(column_name, "ブ", "ぶ");
UPDATE table_name SET column_name = REPLACE(column_name, "ベ", "べ");
UPDATE table_name SET column_name = REPLACE(column_name, "ボ", "ぼ");

UPDATE table_name SET column_name = REPLACE(column_name, "パ", "ぱ");
UPDATE table_name SET column_name = REPLACE(column_name, "ピ", "ぴ");
UPDATE table_name SET column_name = REPLACE(column_name, "プ", "ぷ");
UPDATE table_name SET column_name = REPLACE(column_name, "ペ", "ぺ");
UPDATE table_name SET column_name = REPLACE(column_name, "ポ", "ぽ");

UPDATE table_name SET column_name = REPLACE(column_name, "マ", "ま");
UPDATE table_name SET column_name = REPLACE(column_name, "ミ", "み");
UPDATE table_name SET column_name = REPLACE(column_name, "ム", "む");
UPDATE table_name SET column_name = REPLACE(column_name, "メ", "め");
UPDATE table_name SET column_name = REPLACE(column_name, "モ", "も");

UPDATE table_name SET column_name = REPLACE(column_name, "ヤ", "や");
UPDATE table_name SET column_name = REPLACE(column_name, "ユ", "ゆ");
UPDATE table_name SET column_name = REPLACE(column_name, "ヨ", "よ");
UPDATE table_name SET column_name = REPLACE(column_name, "ャ", "ゃ");
UPDATE table_name SET column_name = REPLACE(column_name, "ュ", "ゅ");
UPDATE table_name SET column_name = REPLACE(column_name, "ョ", "ょ");

UPDATE table_name SET column_name = REPLACE(column_name, "ラ", "ら");
UPDATE table_name SET column_name = REPLACE(column_name, "リ", "り");
UPDATE table_name SET column_name = REPLACE(column_name, "ル", "る");
UPDATE table_name SET column_name = REPLACE(column_name, "レ", "れ");
UPDATE table_name SET column_name = REPLACE(column_name, "ロ", "ろ");

UPDATE table_name SET column_name = REPLACE(column_name, "ワ", "わ");
UPDATE table_name SET column_name = REPLACE(column_name, "ヲ", "を");
UPDATE table_name SET column_name = REPLACE(column_name, "ン", "ん");

ぱっと調べたところ、これだ！というサンプルが無かったので備忘がてら。