Question

我正在写一个程序。在某些地方，我想在我的本地数据库中插入一些值。但是如果插入后检查数据库是空的。这是代码

LeaderBase sqh = new LeaderBase(this);
    SQLiteDatabase sqdb = null;
    if (checkDataBase()){

        sqdb = SQLiteDatabase.openDatabase("/data/data/com.example.test7/databases/leader_database.db", null, 0);
    }
    else{

    }

    sqdb = sqh.getWritableDatabase();

    ContentValues cv = new ContentValues();
    cv.put(LeaderBase.USERNAME, String.valueOf(nameRes));
    cv.put(LeaderBase.USERMONEY, moneyRes);
    cv.put(LeaderBase.USERTIME, timeRes);
    cv.put(LeaderBase.UGAMETYPE, gtype);

    sqdb.insert(LeaderBase.TABLE_NAME, null, cv);

    Cursor cursor2 = sqdb.query(LeaderBase.TABLE_NAME, new String[] {
            LeaderBase._ID, LeaderBase.USERNAME }, 
            null, // The columns for the WHERE clause
            null, // The values for the WHERE clause
            null, // don't group the rows
            null, // don't filter by row groups
            null // The sort order
            );
    int check_count = cursor2.getCount();
    sqdb.close();
    sqh.close();

LeaderBase类的代码：

public class LeaderBase extends SQLiteOpenHelper implements BaseColumns {
private static final String DATABASE_NAME = "leader_database.db";
private static final int DATABASE_VERSION = 1;

public static final String TABLE_NAME = "leader_board";
public static final String UID = "_id";
public static final String USERNAME = "username";
public static final String USERMONEY = "usermoney";
public static final String USERTIME = "usertime";
public static final String UGAMETYPE = "ugametype";

private static final String SQL_CREATE_ENTRIES = "CREATE TABLE "
        + TABLE_NAME + " (" + UID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
        + USERNAME + " VARCHAR(255)," 
        + USERMONEY + " BIGINT," 
        + USERTIME + "INT," 
        + UGAMETYPE + "INT"+
                ");";

private static final String SQL_DELETE_ENTRIES = "DROP TABLE IF EXISTS "
        + TABLE_NAME;


public LeaderBase(Context context) {
    // TODO Auto-generated constructor stub
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}


@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL(SQL_CREATE_ENTRIES);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
            db.execSQL(SQL_DELETE_ENTRIES);
            onCreate(db);
}

}

问题是如果我检查值check_count则为零。数据库是空的。有什么问题？

感谢所有答案！

Answer 1

我相信您会遇到异常，因为您忘记在列的后面添加一个空格

+ USERTIME + "INT,"+ UGAMETYPE + "INT"+

我建议您使用以下行

更新该行

private static final String SQL_CREATE_ENTRIES = "CREATE TABLE "
    + TABLE_NAME + " (" + UID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
    + USERNAME + " VARCHAR(255)," 
    + USERMONEY + " BIGINT," 
    + USERTIME + " INT,"         
    + UGAMETYPE + " INT"+");";

注意：执行此更改后，只需从设备/模拟器中删除旧应用程序，然后重试。这背后的实际原因是您的create table查询将在onCreate()方法中执行。所以要调用它，你必须卸载以前的应用程序。

插入ContentValues后，Android SQLite为空

1 个答案: