如何在android中的一个活动中进行两个数据库查询调用

发布于 2024-11-16 06:37:30 字数 1391 浏览 2 评论 0原文

我想进行一个 sql 查询并将其放入 TextView 中。我可以通过遵循有关使用适配器/dbHelpers 的教程/示例来为 ListView 执行此操作。我收到 CursorIndexOutOfBoundException 会让我相信我没有正确使用光标。

这是 onCreate 中的代码：

    TextView summaryTV = (TextView) findViewById(R.id.summary);
    sumAllAmounts = iouHelper.getSumAllAmounts();
    startManagingCursor(sumAllAmounts);
    System.out.println(String.valueOf(iouHelper.getSumAllAmounts(sumAllAmounts)));
    summaryTV.setText(String.valueOf(iouHelper.getSumAllAmounts(sumAllAmounts)));

sumAllAmounts 是一个 Cursor，由数据库助手执行 sql 命令返回。我知道 sql 查询是正确的，因为我使用 SQLite 数据库浏览器对其进行了测试。我可以使用 ArrayAdapters 让它在 ListView 上工作。

查询应返回 2 列：id 和 amount。 helper.getSumAllAmounts(Cursor) 将返回第二列 Cursor.getInt(1) 并将其转换为要显示在 TextView 上的字符串。 TextView.setText(String.valueOf(int))

请指导我哪里搞砸了。谢谢。

编辑：

Code for DB helper function:
public Cursor getSumAllAmounts() {
        return (getReadableDatabase().rawQuery("SELECT _id, SUM(amount) FROM ious", null));
    }

public int getSumAllAmounts(Cursor c){
        return (c.getInt(1));
    }

数据库的架构：

public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE ious (_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, type TEXT, amount INT, description TEXT, date String);");
    }

原文

I would like to make a sql query and puts it in a TextView. I am able to do it for a ListView by following tutorials/examples on using adapters/dbHelpers. I am getting CursorIndexOutOfBoundException will leads me to believe I am not using the Cursor properly.

This is the code in onCreate:

    TextView summaryTV = (TextView) findViewById(R.id.summary);
    sumAllAmounts = iouHelper.getSumAllAmounts();
    startManagingCursor(sumAllAmounts);
    System.out.println(String.valueOf(iouHelper.getSumAllAmounts(sumAllAmounts)));
    summaryTV.setText(String.valueOf(iouHelper.getSumAllAmounts(sumAllAmounts)));

sumAllAmounts is a Cursor which is returned by the database helper executing the sql command. I know the sql query is correct because I tested it using SQLite Database Browser. And I am able to get it to work on a ListView using ArrayAdapters.

The query should return 2 column: id and amount. The helper.getSumAllAmounts(Cursor) will return the second column Cursor.getInt(1) and it gets converted to a String to be displayed on the TextView. TextView.setText(String.valueOf(int))

Please guide me as to where I messed up. Thanks.

EDIT:

Code for DB helper function:
public Cursor getSumAllAmounts() {
        return (getReadableDatabase().rawQuery("SELECT _id, SUM(amount) FROM ious", null));
    }

public int getSumAllAmounts(Cursor c){
        return (c.getInt(1));
    }

Schema for the DB:

public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE ious (_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, type TEXT, amount INT, description TEXT, date String);");
    }

分享到QQ

分享到微博