更新SQLite数据库android

Question

好吧，我做了一个数据库，我意识到，每次我改变数据库中的东西我必须卸载，然后重新安装应用程序:(这是非常令人沮丧的... 这里是我的代码为我的数据基地希望你能帮助我，我不知道什么是错我的代码：

import android.content.ContentValues; 
import android.content.Context; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 

public class Cook_tab_snacks_data extends SQLiteOpenHelper { 

public static final String DATABASE_NAME = "Snacks"; 

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

@Override 
public void onCreate(SQLiteDatabase db) { 

    String sql = "CREATE TABLE IF NOT EXISTS snacks (" + 
        "_id INTEGER PRIMARY KEY AUTOINCREMENT, " + 
        "name TEXT, " + 
        "disc TEXT, " + 
        "photo TEXT, " + 
        "prep TEXT, " + 
        "thumb TEXT, " + 
        "ingre TEXT, " + 
        "howto TEXT, " + 
        "info TEXT, " + 
        "snackId INTEGER)"; 
    db.execSQL(sql); 

    ContentValues values = new ContentValues(); 

    values.put("name", "Name 1"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("thumb", "stub.png"); 
    values.put("prep", "takes 30 mins"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

    values.put("name", "Name 2"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("thumb", "ic_launcher.png"); 
    values.put("prep", "takes 500 mins"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

    values.put("name", "Name 3"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("thumb", "stub.png"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

    values.put("name", "Name 4"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

    values.put("name", "Name 5"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

    values.put("name", "Name 6"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

    values.put("name", "Name 7"); 
    values.put("disc", "here is the description"); 
    values.put("photo", "stub.png"); 
    values.put("ingre", "the ingredients of the snack"); 
    values.put("howto", "how to make this thing"); 
    values.put("info", "basically its this much calorie and such and such"); 
    db.insert("snacks", "name", values); 

} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    db.execSQL("DROP TABLE IF EXISTS snacks"); 
    onCreate(db); 
}} 

我似乎无法添加任何物品，或编辑任何项目，而无需反安装应用程序然后再重新安装:(请帮助！ !! 非常感谢！

Answer 1

不是卸载并重新安装应用程序，只需增加数据库的版本号码呼叫onUpgrade方法。

public Cook_tab_snacks_data(Context context) { 
    super(context, DATABASE_NAME, null, 2); //previously 1, now 2 
} 

在你onUpgrade方法，首先它会删除现有的表，然后将调用的onCreate方法重新

Answer 2

你也有，因为数据库只创建一次，如果你想要t o改变任何事情，你必须卸载它。

这是事物的工作方式

Answer 3

你onUpgrade功能是没有得到所谓的，因为表（S）数据库的版本没有变化。如果每次更改数据库时增加版本号，onUpgrade函数都会将其删除并重新创建。

最后输入参数的超构造是数据库的版本号：

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

Answer 4

的SQLiteOpenHelper的onCreate仅当创建数据库调用。

如果你想要将其值添加到数据库中，您可以在活动或服务通过实例化你的子类，调用getWritableDatabase()然后在你onCreate正在做同样的方式调用insert这样做。

如果你想改变模式，你需要在onUpgrade中这样做。

notepad example是学习如何在应用中使用SQLiteDatabase的好地方，如果您需要一些练习。