使用 Eclipse 开发应用程序答案

【问题标题】：App Development using eclipse使用 Eclipse 开发应用程序
【发布时间】：2018-09-03 01:39:34
【问题描述】：

我想使用按钮单击的 where 条件从表中检索最小余额。以下是我的代码，它不起作用请给我解决方案。提前致谢..

smname = spn_mname.getSelectedItem().toString().trim();

yname = spn_yname.getSelectedItem().toString().trim();

scno = spn_count.getSelectedItem().toString().trim();

String dbsyname = null, dbsmname = null, dbsycolor = null, dbscount = null, dbsrqty = null, dbsdqty = null, dbsbaln = null;
DataBaseHelper dbh = new DataBaseHelper(StockActivity.this);

SQLiteDatabase db = dbh.getReadableDatabase();

Cursor cursor = db.rawQuery("SELECT MIN(Balance) FROM stocktable",null);
if (cursor.moveToFirst()) {
    do {
        dbsmname = cursor.getString(cursor.getColumnIndex("Millname"));
        dbsyname = cursor.getString(cursor.getColumnIndex("Yarnname"));
        dbscount = cursor.getString(cursor.getColumnIndex("Counttno"));

        if (dbsmname.equals(smname) 
                && bsyname.equals(syname)
                && dbscount.equals(scno)) {
            dbsbaln = cursor.getString(cursor.getColumnIndex("Balance"));
        }

    } while (cursor.moveToNext());

    edtrqty.setText(dbsbaln);
}

【问题讨论】：

什么问题，是不是崩溃了？
s 它显示不幸的是应用程序已停止
我已经添加了解决方案，试试吧。如果仍然有错误添加崩溃日志

标签： android eclipse sqlite

【解决方案1】：

您只在查询中选择了 MIN(Balance) 并尝试访问 Millname,Counttno 和游标上的其他值将引发异常。

试试下面的解决方案

    Cursor cursor = db.rawQuery("SELECT MIN(Balance) balance as  FROM stocktable 
 where Millname=? AND bsyname=? AND dbscount=?",new String[]{smname,syname,scno});
  if (cursor.moveToFirst()) {
      do {
            dbsbaln = cursor.getString(cursor.getColumnIndex("balance"));
          }

      } while (cursor.moveToNext());
        edtrqty.setText(dbsbaln);

【讨论】：

【解决方案2】：

以下代码完美运行...

Cursor cursor = db.rawQuery("SELECT MIN(Balance) AS balance FROM " + DataBaseHelper.stocktable + " WHERE Millname = ? AND Yarnname = ? AND Counttno = ? ", new String[] { smname, syname, scno });

            if (cursor.moveToFirst()) {
                do {
                    dbsbaln = cursor.getString(cursor
                            .getColumnIndex("balance"));

                } while (cursor.moveToNext());
                edtrqty.setText(dbsbaln);
            }

【讨论】：