问题描述
我有一个问题：我需要从SQLite数据库中删除一列。我写了这个查询
I have a problem: I need to delete a column from my SQLite database. I wrote this query
alter table table_name drop column column_name
但它不起作用。请帮助我。
but it does not work. Please help me.
推荐答案
来自：：
SQLite对ALTER TABLE的支持有限，可用于在$ item的末尾添加
列。表或更改表名。如果
想要对表的结构进行更复杂的更改，则
将不得不重新创建表。您可以将现有数据保存到
临时表中，删除旧表，创建新表，然后将
的数据从临时表中复制回来。
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.
例如，假设您有一个名为 t1的表，其列名为
a， b和 c，并且您要从此$ b $中删除列 c b表。以下步骤说明了如何完成此操作：
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;
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