SQLite学習——ALTER TABLE操作制限
1156 ワード
SQLiteはカラムの名前変更やタイプ変更などの操作をサポートしていません.公式に与えられた方法は、元のテーブルのデータを一時テーブルにバックアップし、元のテーブルを削除してから、新しいテーブル構造を作成し、その後、一時テーブルのデータをインポートすることです.公式には、(11)How do I add or delete columns from an existing table in SQLite.
SQLite has limited ALTER TABLE support that you can use to add a column to the end of a table or to change the name of a table. If you want to make more complex changes in the structure of a table, you will have to recreate the table. You can save existing data to a temporary table, drop the old table, create the new table, then copy the data back in from the temporary table.
For example, suppose you have a table named “t1″ with columns names “a”, “b”, and “c” and that you want to delete column “c” from this table. The following steps illustrate how this could be done:
SQLiteの学習に役立つ公式リンクをいくつかお勧めします.http://www.sqlite.org/syntaxdiagrams.html#column-def http://www.sqlite.org/faq.html#q11
SQLite has limited ALTER TABLE support that you can use to add a column to the end of a table or to change the name of a table. If you want to make more complex changes in the structure of a table, you will have to recreate the table. You can save existing data to a temporary table, drop the old table, create the new table, then copy the data back in from the temporary table.
For example, suppose you have a table named “t1″ with columns names “a”, “b”, and “c” and that you want to delete column “c” from this table. The following steps illustrate how this could be done:
BEGIN TRANSACTION;
CREATE TEMPORARY TABLE t1_backup(a,b);
INSERT INTO t1_backup SELECT a,b FROM t1;
DROP TABLE t1;
CREATE TABLE t1(a,b);
INSERT INTO t1 SELECT a,b FROM t1_backup;
DROP TABLE t1_backup;
COMMIT;SQLiteの学習に役立つ公式リンクをいくつかお勧めします.http://www.sqlite.org/syntaxdiagrams.html#column-def http://www.sqlite.org/faq.html#q11