SQLite自动增量非主键字段 [英] SQLite auto-increment non-primary key field

问题描述

是否可以在每次插入时自动增加一个非主键?

Is it possible to have a non-primary key to be auto-incremented with every insertion?

例如，我想要一个日志，其中每个日志条目都有一个主键(供内部使用)和一个修订号(我要自动递增的INT值).

For example, I want to have a log, where every log entry has a primary key (for internal use), and a revision number ( a INT value that I want to be auto-incremented).

作为一种解决方法，可以使用序列完成此操作，但是我认为SQLite不支持序列.

As a workaround, this could be done with a sequence, yet I believe that sequences are not supported in SQLite.

推荐答案

插入时可以选择max(id)+1.

You can do select max(id)+1 when you do the insertion.

例如:

INSERT INTO Log (id, rev_no, description) VALUES ((SELECT MAX(id) + 1 FROM log), 'rev_Id', 'some description')

INSERT INTO Log (id, rev_no, description) VALUES ((SELECT MAX(id) + 1 FROM log), 'rev_Id', 'some description')

请注意，这将在空表上失败，因为将没有id为0的记录，但是您可以添加第一个虚拟条目或将sql语句更改为此:

Note that this will fail on an empty table since there won't be a record with id is 0 but you can either add a first dummy entry or change the sql statement to this:

INSERT INTO Log (id, rev_no, description) VALUES ((SELECT IFNULL(MAX(id), 0) + 1 FROM Log), 'rev_Id', 'some description')

INSERT INTO Log (id, rev_no, description) VALUES ((SELECT IFNULL(MAX(id), 0) + 1 FROM Log), 'rev_Id', 'some description')

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