android sqlite随机从数据库中获取数据 [英] android sqlite getting data from database randomly

问题描述

我的数据库包含问题，每个问题都有三个选项.一切正常，但是当我尝试随机获取问题和选项时，它给了我错误:

my database contains questions and each question has three options. everything work fine but when I try to get the questions and options randomly it it gives me errors:

我发现了与我的问题类似的问题，但它也不起作用，

I found similar questions to my problem but it also didn't work,

这是我的代码:

public List<Test> getTest() {
List<Test> MyList = new ArrayList<Test>();

myDB=this.getReadableDatabase();
Cursor cursor = myDB.rawQuery("SELECT  * FROM " + My_Table + "ORDER BY RANDOM() LIMIT 1", null);

if (cursor.moveToFirst()) {
do {
Test newQ = new Test();
newQ .setId(cursor.getInt(0));
newQ .setTest(cursor.getString(1));
newQ .setAns(cursor.getString(2));
newQ .setO1(cursor.getString(3));
newQ .setO2(cursor.getString(4));
newQ .setO3(cursor.getString(5));
MyList .add(newQ );
} while (cursor.moveToNext());
}
return MyList ;}

当我将这一行添加到我的代码中时:

when I add this line to my code:

ORDER BY RANDOM() LIMIT 1

ORDER BY RANDOM() LIMIT 1

该活动将不起作用.

推荐答案

您还需要将 SQL 的 ORDER BY 部分引用为 Java 字符串文字:

You need to quote the ORDER BY part of the SQL as Java string literal as well:

"SELECT  * FROM " + My_Table + " ORDER BY RANDOM() LIMIT 1"

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