Question

我使用以下代码来获取过去两个月的数据。

 public List<String> getDates() {
        SQLiteDatabase db       = this.getReadableDatabase();
        List<String>   dateList = new ArrayList<>();

        String query = "SELECT DISTINCT " + KEY_PROGRESSDATE + " FROM " + TABLE_ENTRY + " WHERE progressdate >= date('now','start of month','-1 month') AND progressdate < date('now','start of month') desc";

        Cursor c = db.rawQuery(query, null);
        if (c.getCount() > 0) {
            while (c.moveToNext()) {
                dateList.add(c.getString(0));
            }
        }
        return dateList;
    }

但我得到了以下错误消息..

引起：android.database.sqlite.SQLiteException：靠近“desc”：语法错误（代码1）:,编译时：SELECT DISTINCT progressdate FROM条目WHERE progressdate＆gt; = date（'now'，'start of month'，' - 1 月'）和progressdate＆lt; date（'now'，'start of month'）desc

为什么会这样？

Answer 1

对于此例外，您必须编写ORDER BY "Columname" DESC

在这里，它会像

SELECT DISTINCT progressdate FROM entry WHERE progressdate >= date('now','start of month','-1 month') AND progressdate < date('now','start of month') ORDER BY progressdate desc

检查example here

Answer 2

您未在查询中使用任何Order By子句。也许您正试图按降序排列进度日期？

String query = "SELECT DISTINCT " + KEY_PROGRESSDATE + " FROM " + TABLE_ENTRY + " WHERE progressdate >= date('now','start of month','-1 month') AND progressdate < date('now','start of month') ORDER BY progressdate desc";

Answer 3

如果函数已经存在，为什么要使用原始查询。尝试使用以下函数从任何表中获取值只需传递参数：

public String[] getValues(boolean b, String table, String column,
                              String where, String orderBy) {
        ArrayList<String> savedAns = new ArrayList<String>();
        Cursor result = null;
        String[] y;
        try {
            result = db.query(b, table, new String[]{column}, where, null,
                    null, null, orderBy, null);
            if (result.moveToFirst()) {
                do {
                    savedAns.add(result.getString(result.getColumnIndex(column)));
                } while (result.moveToNext());
            } else {
                return null;
            }
            y = savedAns.toArray(new String[result.getCount()]);
        } finally {
            result.close();
        }
        return y;
    }

希望它可以帮助你..

无法使用sqlite查询

3 个答案: