Question

我需要做的是在某个商店获取某个用户的积分，我运行它;

                Cursor cursor1 = myDB.checkPointss(email, name);
                String one = cursor1.getString(cursor1.getColumnIndex("POINTS"));

                scanText.setText("barcode resueeeelt " + one);

这是方法;

public Cursor checkPointss(String email, String name) {
    Cursor c = db.rawQuery("SELECT * FROM compdata WHERE EMAIL= ? AND NAME=?", new String[] {email, name});
    if (c != null) {
        c.moveToFirst();
    }
    return c;

}

每当我尝试登录页面时，它会因为试图获得积分而崩溃？我尝试了很多不同的代码，但似乎都没有。

所以我只想让它找到包含该用户名和商店名称的行的点，然后在点上添加一定数量并更新数据库。

02-18 20:07:42.694  15570-15570/com.adventorious.quickrewards E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.adventorious.quickrewards, PID: 15570
    java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
            at android.database.CursorWindow.nativeGetString(Native Method)
            at android.database.CursorWindow.getString(CursorWindow.java:439)
            at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
            at com.adventorious.quickrewards.Scan$3.onPreviewFrame(Scan.java:155)
            at android.hardware.Camera$EventHandler.handleMessage(Camera.java:1016)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5602)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
            at dalvik.system.NativeStart.main(Native Method)

这项工作;

public boolean checkPoints(String email, String name){
    Cursor c = db.rawQuery("SELECT POINTS FROM compdata WHERE EMAIL= ? AND NAME=?", new String[] {email, name});
    if(c.moveToFirst()) {
        return true;
    }  else {
        return false;

    }
}

那为什么不能获取数据呢？

Answer 1

getColumnIndex()区分大小写，而SQL则不区分大小。

如果表中的列是小写的，它在SELECT *结果集中将为小写，并且尝试使用大写列名称检索它将不起作用。

从光标获取数据

1 个答案: