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書籍番号 idと書籍の部数を指定すると、書籍の部数と同じ数の行をテーブルに挿入したいと考えています。これは私の機能しないソリューションです:

DROP PROCEDURE IF EXISTS insert_into_book_copy_table;
CREATE PROCEDURE insert_into_book_copy_table (IN in_book_id INT,
                                              IN in_num     INT)
BEGIN

    SET @I = 1;
    SET @ACQUIRED = CURRENT_TIMESTAMP;

    WHILE I <= in_num DO 
        INSERT INTO book_copy (book_id, acquired) # The table has an
        VALUES (in_book_id, @ACQUIRED);           # auto-increment field
                                                  # which I didn't list here
        SET @I = @I + 1;
    END WHILE;

END$$

たとえば、指定された書籍番号 IDが 23 で、書籍の部数が 8 の場合、book_copy テーブルは次のようになります。

SELECT * FROM book_copy;
╔══════════════╦══════════╦═════════════════════╗
║ book_copy_id ║  book_id ║      acquired       ║
╠══════════════╬══════════╬═════════════════════╣
║            1 ║       23 ║ 2013-04-15 18:15:20 ║
║            2 ║       23 ║ 2013-04-15 18:15:20 ║
║            3 ║       23 ║ 2013-04-15 18:15:20 ║
║            4 ║       23 ║ 2013-04-15 18:15:20 ║
║            5 ║       23 ║ 2013-04-15 18:15:20 ║
║            6 ║       23 ║ 2013-04-15 18:15:20 ║
║            7 ║       23 ║ 2013-04-15 18:15:20 ║
║            8 ║       23 ║ 2013-04-15 18:15:20 ║
╚══════════════╩══════════╩═════════════════════╝

そして、これをコーディングするより良い方法はありますか?

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1 に答える 1

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単一の SQL ステートメントとして、これを試してください:-

INSERT INTO book_copy (book_id, acquired)
SELECT a.i+b.i*10+c.i*100 + 1, $BookId, NOW()
FROM integers a, integers b, integers c
WHERE a.i+b.i*10+c.i*100 < $NumberToInsert

0 から 9 の値を持つ 10 行の 1 つの列 (i と呼ばれる) を持つ整数のテーブルに依存します。これをそれ自体に対して 2 回結合すると、0 から 999 までのすべての数値が得られます (簡単に拡張できます)。 1 つのステートメントで 1000 本。

編集-整数のテーブルを作成したくない場合は、定数を返すいくつかのサブクエリで同じことを行うことができます:-

INSERT INTO book_copy (book_id, acquired)
SELECT a.i+b.i*10+c.i*100 + 1, $BookId, NOW()
FROM (SELECT 0 AS i UNION SELECT 1 AS i UNION SELECT 2 AS i UNION SELECT 3 AS i UNION SELECT 4 AS i UNION SELECT 5 AS i UNION SELECT 6 AS i UNION SELECT 7 AS i UNION SELECT 8 AS i UNION SELECT 9 AS i ) a,
(SELECT 0 AS i UNION SELECT 1 AS i UNION SELECT 2 AS i UNION SELECT 3 AS i UNION SELECT 4 AS i UNION SELECT 5 AS i UNION SELECT 6 AS i UNION SELECT 7 AS i UNION SELECT 8 AS i UNION SELECT 9 AS i ) b,
(SELECT 0 AS i UNION SELECT 1 AS i UNION SELECT 2 AS i UNION SELECT 3 AS i UNION SELECT 4 AS i UNION SELECT 5 AS i UNION SELECT 6 AS i UNION SELECT 7 AS i UNION SELECT 8 AS i UNION SELECT 9 AS i ) c
WHERE a.i+b.i*10+c.i*100 < $NumberToInsert
于 2013-04-15T15:06:50.577 に答える