重置Android Room库中的自动增量 [英] Reset auto-increment in Android's Room library

问题描述

我使用Android的Room库创建了一个表，该表存储了User类型的项目.对于ID列，该值是通过添加注释自动生成的

I created a table using Android's Room library, which stores items of type User. For the ID column, the value is automatically generated by adding the annotation

@PrimaryKey(autoGenerate = true)

在下一个应用程序运行中，我删除表中的所有条目.但是，自动生成的值不会重置为0，而是会在上一次运行的左侧继续.

In the next application run, I delete all entries in the table. However, the auto-generated value is not reset to 0, but continues where it left of the previous run.

删除表中的所有条目时如何重置自动递增计数器?

How can I reset the auto-increment counter when I delete all entries in a table?

推荐答案

您为什么要问这个更相关的问题.具有AUTOINCREMENT的列将是 rowid 列的别名，该列用于唯一标识行.除了识别行之外，最好不要依靠此值.

Why would you, is perhaps the more pertinent question. A column with AUTOINCREMENT will be an alias of the rowid column which is used to uniquely identify a row. It isn't the best practice to rely upon this value other than for identifying a row.

使用AUTOINCREMENT(autogenerate = true)会创建一个内部表 sqlite_sequence ，该表中的一行包含有史以来使用量最高的 rowid 的值，下一个 rowid 将是该值+1.因此是您的问题.

Using AUTOINCREMENT (autogenerate = true) results in an internal table sqlite_sequence being created, a row in that table holds the value of the highest ever used rowid The next rowid will be that values + 1. Hence your issue.

要从1重新开始，您必须将 sqlite_sequence 表中的相应行更新为0，或删除 sqlite_sequence 表中的相应行.

As such to restart from 1 you would have to either update the respective row in the sqlite_sequence table to 0 or delete the respective row in the sqlite_sequence table.

您不妨查看

You may wish to have a look at Android Room - reset auto generated key on each app run. Noting that this could be the basis for resetting the sequence value, but that it will always resets the sequence value.

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