QUERY给光标带来异常

Question

查询 - 虽然获取param_name和param_value它给我绑定的异常索引 - 虽然它正常工作，直到昨天突然它开始给出错误。

Cursor cur = db 
      .rawQuery("SELECT SP.PARAM_NAME AS PARAM_NAME, SRD.PARAM_VALUE AS PARAM_VALUE FROM QT_UM_SHED_READY SR, " 
        +" QT_UM_SHED_READY_DTL SRD LEFT OUTER JOIN QM_UM_SHED_PARAM SP " 
        +" ON SP.PARAM_ID = SRD.PARAM_ID WHERE SR.MOB_ID=SRD.MOB_ID " 
        +" AND SR.MEMBER_ID" + "=? " + "AND SR.ENTRY_DATE = (SELECT MAX (ENTRY_DATE) FROM QT_UM_SHED_READY)" , new String[] { memberId }); 


    String param_Name = cur.getString(cur.getColumnIndex("PARAM_NAME")); 
    String param_Value = cur.getString(cur.getColumnIndex("PARAM_VALUE")); 

logcat的

10-23 06:20:54.891: W/dalvikvm(1121): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
10-23 06:20:55.071: E/AndroidRuntime(1121): FATAL EXCEPTION: main 
10-23 06:20:55.071: E/AndroidRuntime(1121): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.manacle.umma.activity/com.manacle.umma.activity.ShedReports}: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 0 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.os.Looper.loop(Looper.java:137) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at java.lang.reflect.Method.invoke(Method.java:511) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at dalvik.system.NativeStart.main(Native Method) 
10-23 06:20:55.071: E/AndroidRuntime(1121): Caused by: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 0 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.database.AbstractCursor.checkPosition(AbstractCursor.java:424) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at com.manacle.umma.activity.HeaderDb.getShedRep(HeaderDb.java:4145) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at com.manacle.umma.activity.ShedReports.onCreate(ShedReports.java:95) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.Activity.performCreate(Activity.java:5104) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
10-23 06:20:55.071: E/AndroidRuntime(1121):  ... 11 more 

Answer 1

如果您还没有一个有效的记录，您不能得到一个列索引;您需要先打电话给moveToFirst或moveToNext第一个：

Cursor cur = db.rawQuery(...); 

// for multiple records: 
while (cur.moveToNext()) { 
    String param_Name = cur.getString(cur.getColumnIndex("PARAM_NAME")); 
    String param_Value = cur.getString(cur.getColumnIndex("PARAM_VALUE")); 
    ... 
} 

// alternatively, for a single record: 
if (cur.moveToFirst()) { 
    String param_Name = cur.getString(cur.getColumnIndex("PARAM_NAME")); 
    String param_Value = cur.getString(cur.getColumnIndex("PARAM_VALUE")); 
}