您正在查询 event_db 表，它是您的数据库的名称，而不是您的表

You are querying the event_db table which is the name of your database, not your table

Cursor c = db.rawQuery("SELECT * FROM "+ "event_db",null);

你应该查询_table表

Cursor c = db.rawQuery("SELECT * FROM "+ "_table",null);

顺便说一句，如果您将数据库命名为 db(我怀疑您无论如何都需要多个 db)和您的表 _event(您可以有许多表，您应该根据它们的角色命名它们，而不仅仅是 _table)

By the way it would be more clear if you name your database db (I doubt you need more than one db anyway) and your table _event (you can have many tables and you should name them accordingly to their role and not just _table)