好的，我创建了一个数据库，我意识到每次我更改数据库中的某些内容时，我都必须卸载然后重新安装应用程序:(这非常令人沮丧...这是我的数据库代码，希望你能帮助我！我不知道我的代码有什么问题:
Okay, I made a database and i realised that each time i change something in the database i have to uninstall then reinstall the Application :( which is very frustrating... here is my code for my data base hopefully you can help me ! i dont know whats wrong with my code:
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项目，或编辑任何项目，而无需卸载应用程序然后重新安装:(请帮助！！！非常感谢！
I can't seem to add any item , or edit any item without having to unistall the application then reinstalling :( HELP PLEASE!!! thanks alot!
无需再次卸载和安装应用程序，只需增加数据库的版本号即可调用 onUpgrade 方法.
Instead of uninstalling and installing the application again, simply increment the version number of your database to call onUpgrade method.
public Cook_tab_snacks_data(Context context) {
super(context, DATABASE_NAME, null, 2); //previously 1, now 2
}
与您的 onUpgrade 方法一样，它首先会删除现有表，然后调用 onCreate 方法重新创建表
as in your onUpgrade method, first it will delete the existing table and then will call onCreate method to recreate the table(s)
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