这是你的助手类

Question

我有一个关于在SQLite中使用WHERE子句的一般问题。我曾经和SQLite合作过，并且知道我的方法。但是，我遇到了WHERE子句的问题。

我有一个Android应用程序，我需要使用SQLite WHERE子句进行一些简单的操作。然而，尽管整天都在试验WHERE条款，但我还是空了。我正在尝试执行非常简单的SQLite命令（例如SELECT name FROM tablename WHERE _id=2或DELETE FROM tablename WHERE name='somename'）。但是，每次我使用where子句时，我都会返回0行（在SELECT的情况下）或删除0行。

表名是正确的。列名是正确的。（只要我没有指定WHERE子句，我就没有选择或插入任何问题。）我确保查询/语句格式正确。我已经尝试了两个原始查询/语句以及方法（我确保使用SELECT和DELETE的正确方法{eg rawQuery()或query() for SELECT}）{{1在Android中有类，但没有有效。

我需要的是能够使用WHERE子句执行简单的查询/语句。有没有人对发生的事情有任何见解？

以下是创建我正在使用的表的代码：

SQLiteDatabase

示例查询 public static final String TABLE_WORKOUTS = "workouts" public static final String W_ID = "_id"; public static final String W_WORKOUT_NAME = "workout_name"; public static final String W_EXERICSE_NAME = "exercise_name"; public static final String W_EXERCISE_SETS = "exercise_sets"; public static final String W_EXERCISE_FIRST_ATTRIBUTE = "first_attribute"; public static final String W_EXERCISE_SECOND_ATTRIBUTE = "second_attribute"; public static final String W_EXERCISE_TYPE = "exercise_type"; private static final String createTableWorkouts = "CREATE TABLE " + TABLE_WORKOUTS + " (" + W_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + W_WORKOUT_NAME + " TEXT, " + W_EXERICSE_NAME + " TEXT, " + W_EXERCISE_SETS + " TEXT, " + W_EXERCISE_FIRST_ATTRIBUTE + " TEXT, " + W_EXERCISE_SECOND_ATTRIBUTE + " TEXT, " + W_EXERCISE_TYPE + " TEXT);";

示例记录（_id，exercise_name，exercise_name，sets，first_attribute，second_attribute，exercise_type）： 23，上半身，卧推，5,160,5，重量

Answer 1

exercise_name列中的值为Bench Press，但您尝试将其与Some Workout匹配。

Answer 2

这是一个可行的源代码，它将使用where条件从SQLite数据库中检索值列表。通过使用游标，检索值并添加到POJO类中。我认为这段代码可以帮到你。

public List<RationNamesPOJO> fetchRationMembers(String rationNumber) {

    ArrayList<RationNamesPOJO> RationDet = new ArrayList<RationNamesPOJO>();

    SQLiteDatabase db = this.getWritableDatabase();

    Cursor cur = db.rawQuery("SELECT * FROM " + TABLE_NAME + " where " + PEOPLE_RATION_NUMBER + "='" + rationNumber + "'", null);

    if (cur.moveToFirst()) {
        do {

            RationNamesPOJO rationPojo = new RationNamesPOJO();
            rationPojo.setPeople_rationNumber(cur.getString(cur.getColumnIndex(PEOPLE_RATION_NUMBER)));
            rationPojo.setPeople_aadhaarNumber(cur.getString(cur.getColumnIndex(PEOPLE_AADHAAR_NUMBER)));
            rationPojo.setPeopleName(cur.getString(cur.getColumnIndex(PEOPLE_NAME)));
            rationPojo.setPeopleBiometric(cur.getString(cur.getColumnIndex(PEOPLE_FINGER_IMAGE)));

            RationDet.add(rationPojo);

        } while (cur.moveToNext());
    }

    return RationDet;

}

Answer 3

你可以这样试试。

实施1

String sqlQuery = "select * from Appointment where start_date='"
                + startDate + "' order by start_date,time(start_date) ASC";

        cursor = getReadableDatabase().rawQuery(sqlQuery, null);
        // Log.e("Appointment ->","Total rows fetched for date "+
        // startDate+" "+cursor.getCount());
        if (cursor != null && cursor.moveToFirst()) {
            do {

            } while (cursor.moveToNext());

}

实施2

private boolean isRequestExists(int requestId) {
    Cursor cursor = null;
    boolean result = false;
    try {
        String[] args = { "" + requestId };
        StringBuffer sbQuery = new StringBuffer("SELECT * from ").append(
                TABLE_NAME).append(" where _id=?");
        cursor = getReadableDatabase().rawQuery(sbQuery.toString(), args);
        if (cursor != null && cursor.moveToFirst()) {
            result = true;
        }
    } catch (Exception e) {
        Log.e("Requestdbhelper", e.toString());
    }
    return result;
}

Answer 4

您好，您可以尝试使用帮助程序类

            Cursor cur1 = null, cur2 = null;
            if (mySQLiteAdapter == null || !mySQLiteAdapter.isOpen()) {
                mySQLiteAdapter = new SqliteAdapter(
                        LoginActivity.this);
            }

            try {
                cur1 = mySQLiteAdapter
                        .executeSQLQuery(
                                "select ifnull(max(login_id),0) as userCount from  table_login",
                                null);

                for (cur1.moveToFirst(); !(cur1.isAfterLast()); cur1
                        .moveToNext()) {
                    userCount = cur1.getString(cur1
                            .getColumnIndex("userCount"));

                }
            } catch (Exception ex) {
                Log.w("error while retrieving cursor values", ex.toString());
            } finally {
                cur1.close();
                if (mySQLiteAdapter != null || mySQLiteAdapter.isOpen()) {
                    mySQLiteAdapter.close();
                }
            }

==========================================

这是你的助手类

   public Cursor executeSQLQuery(String sql, String[] selectionArgs) {
    Cursor cursor = null;
    try {
        if (database != null) {
            cursor = database.rawQuery(sql, selectionArgs);
        }
    } catch (SQLiteException sqle) {
        Toast.makeText(context,
                "Unable to execute sql query \n" + sqle.getMessage(),
                Toast.LENGTH_SHORT).show(); 
    }
    return cursor;
}

在SQLite中使用WHERE子句

4 个答案:

这是你的助手类