“没有这样的表"在SQLite Android中发现错误 [英] "No Such Table" Error found in SQLite Android

问题描述

我试图学习SQLite数据库，但是我真的很讨厌热情地处理任何后端内容.我已经遇到了一个看似简单的问题.

I am trying to learn about SQLite databases, but I really hate dealing with any back-end stuff, with a passion. I'm already hitting walls with a seemingly simple problem.

这是我认为与DatabaseHelper类有关的代码

Here is the code that I think matters from the DatabaseHelper class

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "Library";

    public static final String TABLE_NAME = "books";
    public static final String TITLE = "title";
    public static final String AUTHOR = "author";
    public static final String ISBN = "isbn";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + TABLE_NAME + " (id INTEGER PRIMARY KEY AUTOINCREMENT, title TEXT, author TEXT, isbn TEXT)");
    }


    public boolean insertBook(String title, String author, String isdn) {

        try {
            SQLiteDatabase db = getWritableDatabase();

            ContentValues cv = new ContentValues();
            cv.put(TITLE, title);
            cv.put(AUTHOR, author);
            cv.put(ISBN, isdn);

            db.insert(TABLE_NAME, null, cv);
            db.close();

            return true;
        } catch (Exception exp) {
            exp.printStackTrace();

            return false;
        }
    }
}

这是我主要活动中的代码

And this is the code in my main activity

dbHelper = new DatabaseHelper(this);

dbHelper.insertBook("Harry Potter", "JK", "1000");
dbHelper.insertBook("Hamlet", "Shakespeare", "500");

Eclipse告诉我insertBook()方法中有错误.它说有no such table books: ....我不知道我在做什么错.使它更令人沮丧的是，在它完美运行之前只有几分钟，然后(我认为)我放下了表，无论出于什么原因，它只是再次创建了表，即使自从我第一次创建表以来，该代码并没有发生变化(我认为...).

Eclipse is telling me that there is an error in the insertBook() method. It says that there is no such table books: .... I have no idea what I am doing wrong here. What makes it more frustrating is that only a couple of minutes before it was working perfectly, then (I think) I dropped the table and it just create it again for whatever reason, even though this code has not changed since I first created it (I think...).

推荐答案

您的设备上存在数据库的较旧版本，该数据库确实具有(空)数据库，但没有books表.如果您可以选择该选项，则只需卸载并重新安装该应用程序即可.

There is an older version of the database on your device, which does have the (empty) database in place, but not the books table. If that's an option for you, just uninstall and reinstall the app.

稍后，当您想在最终用户设备上生产期间向数据库中添加新表，但保留现有数据时，用于添加新表，更改架构或升级数据的指定挂钩是您SQLiteOpenHelper的方法.

Later, when you'd like to add a new table to the database during production on end-user devices, but keep existing data, the designated hook to add new tables, alter the schema or upgrade your data is the onUpgrade method of your SQLiteOpenHelper.

这篇关于“没有这样的表"在SQLite Android中发现错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！