ALTER TABLE in sqlite

SQLite不支持通过ALTER TABLE命令对表结构进行修改，例如添加或删除字段，原始说明如下：

(11) How do I add or delete columns from an existing table inSQLite.

SQLite has limitedALTER TABLEsupport 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:

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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;