行不在 SQLite 中创建并检索 AUTOINCREMENT 值 - Android

Question

希望这是允许的 - 我有 2 个不相关的问题。

1. 这是主要问题。出于某种原因，我的数据库中的最后一行没有被创建。我得到一个 SQLiteException。 LogCat 和代码如下。错误代码行已被注释。

2. 有没有办法获取 AUTOINCREMENT 列的值？我无法使用 Cursor c = db.rawQuery("SELECT " + PERCENTAGE + " FROM " + TABLE + " WHERE " + RANK + " = " + rank, null); 访问它，其中 RANK 是 AUTOINCREMENT 列标题。此游标始终返回 0。

DatabaseHelper.java

// Table columns names. 
private static final String RANK = "_id"; 
private static final String SCORE = "score"; 
private static final String PERCENTAGE = "percentage";
private static final String SUM = "sum";

//Check if new record makes the top 10.
public boolean check(long score, int percentage, long sum) {
    Cursor c = db.rawQuery("SELECT " + SUM + " FROM " + TABLE, null);  //Line 82
    int z = c.getCount();
    c.moveToLast();
    int x = c.getInt(c.getColumnIndex(SUM));
    long y = calculateSum(score, percentage);
    if(z != 10) {
        insert(score, percentage, sum);
        return true;
    } else {
        if(y > x) {
            delete(10);
            insert(score, percentage, sum);
            sort();
            return true;
        } else {
            return false;
        }
    }
}

//Insert new record.
public long insert(long score, int percentage, long sum) {
    ContentValues values = new ContentValues();
    values.put(SCORE, score);
    values.put(PERCENTAGE, percentage);
    values.put(SUM, sum);

    return db.insert(TABLE, null, values);
}

public void onCreate(SQLiteDatabase db) {
    db.execSQL("CREATE TABLE " + TABLE + " ("
            + RANK + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + SCORE + " LONG,"
            + PERCENTAGE + " INTEGER,"
            + SUM + " LONG"
            + ");");
}

LogCat 输出

01-04 02:00:24.635: E/AndroidRuntime(6224): FATAL EXCEPTION: main
01-04 02:00:24.635: E/AndroidRuntime(6224): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.Results}: android.database.sqlite.SQLiteException: no such column: sum (code 1): , while compiling: SELECT sum FROM HighscoresList
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.os.Looper.loop(Looper.java:137)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.ActivityThread.main(ActivityThread.java:5039)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at java.lang.reflect.Method.invokeNative(Native Method)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at java.lang.reflect.Method.invoke(Method.java:511)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at dalvik.system.NativeStart.main(Native Method)
01-04 02:00:24.635: E/AndroidRuntime(6224): Caused by: android.database.sqlite.SQLiteException: no such column: sum (code 1): , while compiling: SELECT sum FROM HighscoresList
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:882)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:493)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at com.example.test.DatabaseHelper.check(DatabaseHelper.java:82)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at com.example.test.Results.showResults(Results.java:111)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at com.example.test.Results.onCreate(Results.java:60)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.Activity.performCreate(Activity.java:5104)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-04 02:00:24.635: E/AndroidRuntime(6224):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
01-04 02:00:24.635: E/AndroidRuntime(6224):     ... 11 more

Answer 1

1. 创建表时出现问题。从“总和”列中检索值时，堆栈跟踪显示错误。此错误意味着没有名为“sum”的列。您是否有可能在创建此表之前尝试获取值？

2. 您可以使用 for 循环检索数据：

   for(int i=0;i<z;i++){
   
   int ID = yourCursor.getInt(0);
   
   if(ID==YOUR_NEEDED_ID){
   
     int percantage = yourCursor.getInt(2);
      break; //if you got what you want, cursor could be stopped
    }
   
    yourCursor.moveToNext();
   
   }
   

编辑

升级数据库使用

    @Override
    public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
        // TODO Auto-generated method stub
        onCreate(db);
    }