我目前正在使用SQLite数据库进行Android应用程序，我想创建一个方法来检索与一个所有者关联的所有任务，但是应用程序无法检索它们，而是返回一个异常。我该如何解决这个问题？
这是数据库的代码：
public class SchedulerDbHelper extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "scheduler.db";
public static final String TABLE_NAME = "SCHEDULER_TABLE";
public static final String TASK_NAME = "NAME";
public static final String TASK_YEAR = "YEAR";
public static final String TASK_MONTH = "MONTH";
public static final String TASK_DAY = "DAY";
public static final String TASK_HOUR = "HOUR";
public static final String TASK_MINUTE = "MINUTE";
public static final String TASK_DESCRIPTION = "DESCRIPTION";
public static final String TASK_OWNER = "OWNER";
public SchedulerDbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String query = "CREATE TABLE " + TABLE_NAME + "(" + TASK_NAME + " TEXT PRIMARY KEY, " +
TASK_YEAR + " INTEGER, " + TASK_MONTH + " INTEGER, " + TASK_DAY + " INTEGER, " +
TASK_HOUR + " INTEGER, " + TASK_MINUTE + " INTEGER, " + TASK_DESCRIPTION + " TEXT, " +
TASK_OWNER + " TEXT" + ")";
sqLiteDatabase.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
String query = "DROP TABLE IF EXISTS " + TABLE_NAME;
sqLiteDatabase.execSQL(query);
onCreate(sqLiteDatabase);
}
public void addTask(Task task) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(TASK_NAME, task.getTaskName());
values.put(TASK_YEAR, task.getYear());
values.put(TASK_MONTH, task.getMonth());
values.put(TASK_DAY, task.getDay());
values.put(TASK_HOUR, task.getHour());
values.put(TASK_MINUTE, task.getMinute());
values.put(TASK_DESCRIPTION, task.getDescription());
values.put(TASK_OWNER, loginID);
db.insert(TABLE_NAME, null, values);
db.close();
}
public Task getTask(String taskName){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME, new String[]{TASK_NAME, TASK_YEAR, TASK_MONTH, TASK_DAY, TASK_HOUR, TASK_MINUTE, TASK_DESCRIPTION, TASK_OWNER}, TASK_NAME + " =?",
new String[]{taskName}, null, null, null, null);
if (cursor != null){
cursor.moveToFirst();
}
Task task = new Task(cursor.getString(0), Integer.parseInt(cursor.getString(1)), Integer.parseInt(cursor.getString(2)),
Integer.parseInt(cursor.getString(3)), Integer.parseInt(cursor.getString(4)), Integer.parseInt(cursor.getString(5)),
cursor.getString(6)) ;
return task;
}
public ArrayList<Task> getAllTask(){
ArrayList<Task> taskList = new ArrayList<>();
String selectQuery = "SELECT * FROM " + TABLE_NAME;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
Task task = new Task();
task.setTaskName(cursor.getString(0));
task.setYear(Integer.parseInt(cursor.getString(1)));
task.setMonth(Integer.parseInt(cursor.getString(2)));
task.setDay(Integer.parseInt(cursor.getString(3)));
task.setHour(Integer.parseInt(cursor.getString(4)));
task.setMinute(Integer.parseInt(cursor.getString(5)));
task.setDescription(cursor.getString(6));
taskList.add(task);
} while (cursor.moveToNext());
}
return taskList;
}
public int updateTask(Task task){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(TASK_NAME, task.getTaskName());
values.put(TASK_YEAR, task.getYear());
values.put(TASK_MONTH, task.getMonth());
values.put(TASK_DAY, task.getDay());
values.put(TASK_HOUR, task.getHour());
values.put(TASK_MINUTE, task.getMinute());
values.put(TASK_DESCRIPTION, task.getDescription());
return db.update(TABLE_NAME, values, TASK_NAME + "=?", new String[]{task.getTaskName()});
}
public void deleteTask(Task task){
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_NAME, TASK_NAME + "=?", new String[]{task.getTaskName()});
db.close();
}
public int getTaskCount() {
String countQuery = "SELECT * FROM " + TABLE_NAME;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
cursor.close();
return cursor.getCount();
}
public ArrayList<Task> getAllTaskForUser(){
ArrayList<Task> taskList = new ArrayList<>();
String selectQuery = "SELECT * FROM " + TABLE_NAME + " WHERE " + TASK_OWNER + " = " + loginID;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
Task task = new Task();
task.setTaskName(cursor.getString(0));
task.setYear(Integer.parseInt(cursor.getString(1)));
task.setMonth(Integer.parseInt(cursor.getString(2)));
task.setDay(Integer.parseInt(cursor.getString(3)));
task.setHour(Integer.parseInt(cursor.getString(4)));
task.setMinute(Integer.parseInt(cursor.getString(5)));
task.setDescription(cursor.getString(6));
taskList.add(task);
loginID = cursor.getString(7);
} while (cursor.moveToNext());
}
return taskList;
}
}
这是运行数据库的主片段的代码：
公共类SchedulerFragment扩展了android.support.v4.app.Fragment {
ListView listViewTaskList;
ArrayList<Task> taskList;
SchedulerDbHelper taskDb;
public static String taskPrimary;
public SchedulerFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_scheduler, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
getActivity().setTitle("Scheduler");
taskDb = new SchedulerDbHelper(getActivity());
taskList = taskDb.getAllTaskForUser();
Iterator<Task> i = taskList.iterator();
String[] taskNameArray = new String[taskList.size()];
int index = 0;
FloatingActionButton floatingActionButtonNewTask = getView().findViewById(R.id.floatingActionButtonNewTask);
listViewTaskList = getView().findViewById(R.id.listViewTaskList);
while(i.hasNext()){
Task t = i.next();
taskNameArray[index] = t.getTaskName();
index++;
}
try {
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, taskNameArray);
listViewTaskList.setAdapter(adapter);
} catch (RuntimeException r1) {
}
listViewTaskList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
String taskName = adapterView.getItemAtPosition(i).toString();
taskPrimary = taskName;
TaskDetailFragment tdf = new TaskDetailFragment();
FragmentManager manager = getFragmentManager();
manager.beginTransaction().replace(R.id.frameLayoutContent, tdf, tdf.getTag()).commit();
}
});
floatingActionButtonNewTask.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View view) {
NewSchedulerFragment nsf = new NewSchedulerFragment();
FragmentManager manager = getFragmentManager();
manager.beginTransaction().replace(R.id.frameLayoutContent, nsf, nsf.getTag()).commit();
}
});
}
}
这是我得到的例外：
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.eduhub, PID: 6873
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.eduhub/com.example.android.eduhub.ContentMainActivity}: android.database.sqlite.SQLiteException: no such column: tth980409 (code 1): , while compiling: SELECT * FROM SCHEDULER_TABLE WHERE OWNER = tth980409
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: android.database.sqlite.SQLiteException: no such column: tth980409 (code 1): , while compiling: SELECT * FROM SCHEDULER_TABLE WHERE OWNER = tth980409
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1318)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1257)
at com.example.android.eduhub.SchedulerDbHelper.getAllTaskForUser(SchedulerDbHelper.java:143)
at com.example.android.eduhub.SchedulerFragment.onViewCreated(SchedulerFragment.java:55)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1430)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1740)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1809)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:799)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2580)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2367)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2322)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2229)
at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3221)
at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:3171)
at android.support.v4.app.FragmentController.dispatchActivityCreated(FragmentController.java:192)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:560)
at android.support.v7.app.AppCompatActivity.onStart(AppCompatActivity.java:177)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1248)
at android.app.Activity.performStart(Activity.java:6679)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2609)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
申请已终止。
答案 0 :(得分：2)
价值必须在引号中。
将您的查询更新为
String selectQuery = "SELECT * FROM " + TABLE_NAME + " WHERE " + TASK_OWNER + " = " + "\"" + loginID + "\"";