java - 无法弄清楚为什么 SQL 语句不起作用

Question

我不明白我的说法有什么问题。对我来说似乎是正确的，光标应该包括我的数据库表中的两行。根据 SQLite 网站，支持这种格式的日期(也尝试过其他支持的日期)。

        String statement = "SELECT * FROM " + TABLE_DISTANCE_NAME + " WHERE " + COLUMN_TIME_DISTANCE_ADDED + " BETWEEN " + "2014-07-14" + " AND " + "2014-08-14";
        Log.d("statement", statement);
        Cursor cur = db.rawQuery(statement, null);
        Log.d("cursor amount rows", Integer.toString(cur.getCount()));

        if (cur != null) {
            cur.moveToFirst();
        }    
        int totalDistance = 0;
        while (cur.isAfterLast() == false) {
            Log.d("cursor distance value", Integer.toString(cur.getInt(0)));
            totalDistance += cur.getInt(0);
            cur.moveToNext();
        }
        Log.d("Total Distance traveled = ", Integer.toString(totalDistance));

这就是表格的样子。

日志:

...statement﹕ SELECT * FROM distanceTraveled WHERE timedistadded BETWEEN 2014-07-14 AND 2014-08-14

com.example.RoadTrip D/cursor amount rows﹕ 0
com.example.RoadTrip D/Total Distance traveled =﹕ 0

谢谢

Answer 1

日期常量需要用单引号引起来:

" WHERE " + COLUMN_TIME_DISTANCE_ADDED + " BETWEEN " + "'2014-07-14'" + " AND " + "'2014-08-14'";

如果您在替换后打印出 SQL 语句，这个问题会更明显。这始终是尝试调试此类问题的良好第一步。