Java “中的语法错误”；从registeruser中选择ID，其中用户名=？和密码=？”；

登录我的系统时出现此代码问题。 语法错误，但我似乎无法找到它，希望有人可以帮助！ 我刚刚创建了第二个表来存储用户登录信息，请遵循youtube上的教程

错误：

E/SQLiteLog: (1) near "andpassword": syntax error in "SELECT ID FROM registeruser WHERE username=? 
andpassword=?"
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.locationadmin, PID: 10953
android.database.sqlite.SQLiteException: near "andpassword": syntax error (code 1 SQLITE_ERROR): , while compiling: SELECT ID FROM registeruser WHERE username=?andpassword=?
    at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)

以下是onclicklistener的代码

    mButtonLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String user = mTextUsername.getText().toString().trim();
            String pwd = mTextPassword.getText().toString().trim();
            Boolean res = myDB.checkUser(user, pwd);
            if (res == true)
            {
               Intent UserLoggedIn = new Intent(ActivityLogin.this, com.example.locationadmin.Activities.UserActivity.class);
                startActivity(UserLoggedIn);

            }
            else{
                Toast.makeText(ActivityLogin.this, "Login error", Toast.LENGTH_SHORT).show();

            }
        }
    });

下面是myDatabaseHelper.java中的代码

 @Override
public void onCreate(SQLiteDatabase db) {
    String query = "CREATE TABLE " + TABLE_NAME +
            " (" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
            COLUMN_LOCATION + " TEXT, " +
            COLUMN_COUNTY + " TEXT, " +
            COLUMN_DESCRIPTION + " TEXT, " +
            COLUMN_INROUTE + " TEXT, " +
            COLUMN_LAT + " TEXT, " +
            COLUMN_LONG + " TEXT, " +
            COLUMN_POSITION + " TEXT, " +
            COLUMN_IMG_URL + " TEXT, " +
            COLUMN_IMG_URL2 + " TEXT, " +
            COLUMN_IMG_URL3 + " TEXT );";

    db.execSQL(query);

    String query1 = "CREATE TABLE " + TABLE_REG +
            " (ID INTEGER PRIMARY KEY AUTOINCREMENT, " +
            COL_1 + " TEXT, " +
            COL_2 + " TEXT, " +
            COL_3 + " TEXT );";

    db.execSQL(query1);

}

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


}


public long addUser(String user, String password) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("username", user);
    contentValues.put("password", password);
    long res = db.insert("registeruser", null, contentValues);
    db.close();
    return res;

}

public boolean checkUser(String username, String password) {
    String[] columns = {COL_1};
    SQLiteDatabase db = getReadableDatabase();
    String selection = COL_2 + "=?" + "and" + COL_3 + "=?";
    String[] selectionArgs = {username, password};
    Cursor cursor = db.query(TABLE_REG, columns, selection, selectionArgs, null, null, null);
    int count = cursor.getCount();
    cursor.close();
    db.close();

    if (count > 0)
        return true;
    else
        return false;

}

---

您只需要在“and”中的

前后和
之间留出一个空格

试一试

在助手中的
checkUser
方法中：
String selection=COL_2+“=？”+”和“+COL_3+”=？”
您可能需要在需要的地方添加一些空格。也可以在`和`之后添加空格。但这不应该属于“由打字错误引起的”非主题问题类别吗？两者都是如此。无论如何，对于低级用户来说，清晰的代码示例更好。。答案更清楚。。（评论界面太差）
 String selection = COL_2 + "=?" + " and " + COL_3 + "=?";