SQLite-更改表的列类型? [英] SQLite - alter a table's column type?

问题描述

我正在开始一个涉及小型数据库的项目，并且正在考虑使用SQLite. 如果我创建一个表并且将其中一列定义为文本，但是存储的所有值都是整数-是否可以更改列的数据类型?我正在使用SQLite Manager，但找不到允许我执行此操作的函数.我可以使用SQL命令执行此操作吗，还是它是SQLite的限制? 即使有此限制，也可能可以找到一些方法，用所需的列类型创建一个新表，然后将数据导入其中.

I am starting a project involving a small database and I am considering to use SQLite. If I create a table and I defined one of the columns as text, but all the values stored are integers - is there a way to change the data type of a column? I am using SQLite Manager and I can't find a function that allows me to do that. Can I do it using a SQL command, or is it a restriction of SQLite? Probably, even with this restriction, one can find some way around and create a new table with the required column types and then import data into it.

关于， 尼克

推荐答案

SQLite不完全支持ALTER TABLE语句.您唯一可以做的就是重命名表和/或添加列.如果要重命名列，最好的选择是使用新列的数据类型/名称创建一个新表，并删除旧表以重命名新表.

SQLite does not fully support ALTER TABLE statements. The only thing you can do is rename a table and/or add columns. If you want to rename a column, your best option is to create a new table with the new columns datatype/names, and to drop the old table in order to rename the new one.

让我们说，您有一个表，需要将"field-1"重命名为"field-2": 首先== >>重命名旧表:

Lets say, you have a table and need to rename "field-1" to "field-2": First ==>> rename the old table:

    ALTER TABLE original RENAME TO tmp;

现在基于旧表创建新表，但使用更新的列名:
== >>用更新的列创建一个表

Now create the new table based on the old table but with the updated column name:
==>> create a table with the updated columns

    CREATE TABLE original(
    field_a INT
   , field_b INT
    );

然后从原始表中复制内容.

Then copy the contents across from the original table.

   INSERT INTO origignal(field_a, field_b)
   SELECT field_a, field_b
   FROM tmp;

最后，放下旧桌子.

   DROP TABLE tmp;

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