rawQuery() 游标上对字段槽 0,1 的错误请求

发布于 2024-12-08 05:33:19 字数 1090 浏览 0 评论 0原文

我对 android 还很陌生，我遇到了以下问题。这是我的代码，我试图将数据库中的数据获取到我的列表中。

private List<Model> getModel(int a) {

    dbHelper = new DbHelper(this);
    db = dbHelper.getWritableDatabase();
    Log.d("Model Int: ", "Model int: " +  a);
    sql = "SELECT * FROM shows";
    resultCursor = db.rawQuery(sql, new String [] {});
    resultCursor.moveToFirst();

    List<Model> list = new ArrayList<Model>();
        list.add(get(Html.fromHtml(resultCursor.getString(a)).toString()));

    for (resultCursor.moveToFirst(); resultCursor.moveToNext(); resultCursor
            .isAfterLast()) {

            list.add(get(Html.fromHtml(resultCursor.getString(a))
                    .toString()));

    }

    startManagingCursor(resultCursor);
    resultCursor.close();
    db.close();
    dbHelper.close();

    return list;
}

效果很好，但是当我不想使用 * 而是使用

sql = "SELECT title subtitle FROM Shows";

来获取所有列时。我收到这样的错误

错误/CursorWindow(371)：字段槽 0,1 的请求错误。行数 = 162、列数 = 1

知道出了什么问题吗？

提前致谢。

原文

I am pretty new to android, and I have the following problem.
This is my code where I'm trying to get data from the database into my list.

private List<Model> getModel(int a) {

    dbHelper = new DbHelper(this);
    db = dbHelper.getWritableDatabase();
    Log.d("Model Int: ", "Model int: " +  a);
    sql = "SELECT * FROM shows";
    resultCursor = db.rawQuery(sql, new String [] {});
    resultCursor.moveToFirst();

    List<Model> list = new ArrayList<Model>();
        list.add(get(Html.fromHtml(resultCursor.getString(a)).toString()));

    for (resultCursor.moveToFirst(); resultCursor.moveToNext(); resultCursor
            .isAfterLast()) {

            list.add(get(Html.fromHtml(resultCursor.getString(a))
                    .toString()));

    }

    startManagingCursor(resultCursor);
    resultCursor.close();
    db.close();
    dbHelper.close();

    return list;
}

that works fine, but when i do not want to get all the columns with * but with

sql = "SELECT title subtitle FROM shows";

instead. I get errors like this

ERROR/CursorWindow(371): Bad request for field slot 0,1. numRows =
162, numColumns = 1

Any ideas what's going wrong?

Thanks in advance.

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赴月观长安 2024-12-15 05:33:19

SELECT title subtitle FROM shows

真正的意思

SELECT title AS subtitle FROM shows

是：仅选择一列：title，但在结果集中将该列重命名为“subtitle”。
这称为为列分配别名。
请参阅：http://beginner-sql-tutorial.com/sql-aliases.htm

解决方案
执行：

SELECT title, subtitle FROM shows

现在您正在选择两列。

免责声明
我不保证该链接中信息的质量，网上有很多质量较差的教程。我刚刚查看了“别名”部分，该部分看起来很有用。

SELECT title subtitle FROM shows

Really means

SELECT title AS subtitle FROM shows

In english: select only one column: title, but rename that column to "subtitle" in the resultset.
This is called assigning an alias to a column.
See: http://beginner-sql-tutorial.com/sql-aliases.htm

Solution
Do:

SELECT title, subtitle FROM shows

Now you are selecting two columns.

Disclaimer
I do not vouch for the quality of the info in that link, there are a lot of poor quality tutorials on the net. I just looked at the "alias" section and that section looks useful.

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