有多个行时的 SQLite Select 语句

Question

我想要 select * 来自 table 比较 3 行和 select return 一个 id，我创建了这个方法：

//UserDAO class

private SQLiteDatabase mDatabase;
private DatabaseHelper mDbHelper;

// irelative code

public Long selectUserLogin(String nickname, String chapter, String password) {
    long id;
    String selectQuery = "SELECT  * FROM " +
            DatabaseHelper.TABLE_USERS + " WHERE " +
            DatabaseHelper.COLUMN_USERS_NICKNAME + " = " + nickname + " AND " +
            DatabaseHelper.COLUMN_USERS_CHAPTER + " = " + chapter + " AND " +
            DatabaseHelper.COLUMN_USERS_PASSWORD + " = " + password;

    Log.e(TAG, selectQuery);
    try {
        Cursor cursor = mDatabase.rawQuery(selectQuery, null);
        if (cursor != null)
            cursor.moveToFirst();

        id = cursor.getLong(cursor.getColumnIndex(DatabaseHelper.COLUMN_USERS_ID));

        return id;
    } catch (Exception e){
        e.printStackTrace();
    }
    return null;
}

已经在我的数据库上创建了昵称=q，章节=Q，密码=qqqqqq

这些是我调用方法来测试他的功能的地方

userDAO.selectUserLogin("q", "Q", "qqqqqq");

我用另一种列出我所有用户的方法进行了检查，我得到了我曾经创建的所有用户。

结果如下：

10-09 01:00:18.298 10978-10978/com.org.feedme.cisvmeeting.activities     D/LeaderFragment: User: [
D/LeaderFragment: [1] 1, h, h, G 
D/LeaderFragment: [2] 2, fkfkdk, fjfkdk, SAO 
D/LeaderFragment: [3] 3, Filipe fila, Fil36
D/LeaderFragment: [4] 4, q, Q, qqqqqq
D/LeaderFragment: [5] 5, glgl, vmlc, GOLGO]

当我试图在 Android 设备监视器上查看我的数据文件夹时，该文件夹是空的，所以如果我无法访问数据库或者我没有正确插入，我会有点困惑。

我 logcat 的一部分，当我尝试调用方法 selectUserLogin:

10-09 00:46:01.198 7745-7745/com.org.feedme.cisvmeeting.activities E/UserDAO: SELECT * FROM users WHERE nickname = q AND chapter = Q AND password = qqqqqq

10-09 00:46:01.208 7745-7745/com.org.feedme.cisvmeeting.activities E/SQLiteLog: (1) no such column: q

10-09 00:46:01.208 7745-7745/com.org.feedme.cisvmeeting.activities W/System.err: android.database.sqlite.SQLiteException: no such column: q (code 1): , while compiling: SELECT * FROM users WHERE nickname = q AND chapter = Q AND password = qqqqqq

编辑：我的 android 设备上只有运行我的应用程序！

EDIT_2: 我测试了另一种类似的方法，第二种方法工作正常！

public String selectUser(long id) {
    String selectQuery = "SELECT  * FROM " + DatabaseHelper.TABLE_USERS +
            " WHERE " + DatabaseHelper.COLUMN_USERS_ID + "=" + id ;
    String result = null;
    Log.e(TAG, selectQuery);
    Cursor cursor = mDatabase.rawQuery(selectQuery, null);
    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        result = cursor.getString(cursor.getColumnIndex(DatabaseHelper.COLUMN_USERS_NAME));
    }
    return result;
}

Answer 1

您需要用引号将字符串参数括起来，因为您没有使用 selectionArgs（rawQuery 中的第二个参数）。

String selectQuery = "SELECT  * FROM " +
        DatabaseHelper.TABLE_USERS + " WHERE " +
        DatabaseHelper.COLUMN_USERS_NICKNAME + " = '" + nickname + "' AND " +
        DatabaseHelper.COLUMN_USERS_CHAPTER + " = '" + chapter + "' AND " +
        DatabaseHelper.COLUMN_USERS_PASSWORD + " = '" + password + "' ";

Log.e(TAG, selectQuery);
try {
    Cursor cursor = mDatabase.rawQuery(selectQuery, null);

或者您可以这样做，它会为您处理字符串。

String selectQuery = "SELECT  * FROM " +
        DatabaseHelper.TABLE_USERS + " WHERE " +
        DatabaseHelper.COLUMN_USERS_NICKNAME + "=? AND " +
        DatabaseHelper.COLUMN_USERS_CHAPTER + "=? AND " +
        DatabaseHelper.COLUMN_USERS_PASSWORD + "=? ";

String[] selectionArgs = new String[] { nickname, chapter, password };

Log.e(TAG, selectQuery);
try {
    Cursor cursor = mDatabase.rawQuery(selectQuery, selectionArgs);

Answer 2

首先，您在设备上删除您的应用程序，然后重新安装该应用程序，现在插入您需要的数据，现在无论您输入的数据是什么，都会记住并将这些数据应用到 select 的查询参数中。

有多个行时的 SQLite Select 语句

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android

android-sqlite