儘管ID已更改爲_id

Question

列'_id'不存在雖然我已將ID重命名爲_id，但仍得到column '_id' does not exist ...我錯過了任何內容嗎？

MyDatabaseelper.java

public class MyDatabaseHelper extends SQLiteOpenHelper { 
    public static final int DATABASE_VERSION=1; 
    public static final String DATABASE_NAME="alm.db"; 
    public static final String TABLE_INFO="Information"; 
    public static final String TABLE_WORKFORCE="WorkForce"; 
    public static final String TABLE_WORKDETAILS="WorkDetails"; 
    public static final String Subcontractors="Subcontractors"; 
    public static final String NumberOfPerson="NumberOfPerson"; 
    public static final String NumberOfHours="NumberOfHours"; 
    public static final String ID="_id"; 
    public static final String TimeIn_Info="timeIn_Info"; 
    public static final String TimeOut_Info="timeOut_Info"; 

    public void onCreate(SQLiteDatabase db) { 
     db.execSQL("create table " + TABLE_INFO + "(ID INTEGER PRIMARY KEY ,Name TEXT,Weather TEXT, Date DATETIME, Status Text, TimeIn_Info DATE TIME, TimeOut_Info DATETIME)"); 
     db.execSQL("create table " + TABLE_WORKFORCE + "(ID INTEGER PRIMARY KEY ,Subcontractors TEXT,NumberOfPerson INTEGER,NumberOfHours TEXT, TInfo_id INTEGER, FOREIGN KEY(TInfo_id) REFERENCES "+TABLE_INFO+"(ID))"); 

} 

ListDisplay.java

public class ListDisplay extends AppCompatActivity { 
    InfoAPI sqlcon; 
    private SimpleCursorAdapter dataAdapter; 


    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.listdisplay1); 
     sqlcon = new InfoAPI(this); 
     final String name1 = getIntent().getExtras().getString("name"); 
     BuildList(name1); 
    } 

    public void BuildList(String name) { 
     final String name1 = name; 
     sqlcon.open(); 
     Cursor cursor=sqlcon.readEntry(name1); 

     String[] columns=new String[]{ 
       MyDatabaseHelper.Weather,MyDatabaseHelper.Date,MyDatabaseHelper.Status,MyDatabaseHelper.TimeIn,MyDatabaseHelper.TimeOut 
     }; 

     int[] to=new int[]{ 
       R.id.weather,R.id.date,R.id.status,R.id.in,R.id.out 
     }; 

     // create the adapter using the cursor pointing to the desired data 
     //as well as the layout information 
     dataAdapter = new SimpleCursorAdapter(
       this, R.layout.listdispaly, 
       cursor, 
       columns, 
       to, 
       0); 

     ListView listView = (ListView) findViewById(R.id.listView1); 
     // Assign adapter to ListView 
     listView.setAdapter(dataAdapter); 






    } 

} 

InfoAPI.java

public Cursor readEntry(String name) 
    { 
     Cursor c=database.rawQuery("SELECT Weather, Date, Status, TimeIn_Info, TimeOut_Info FROM " + MyDatabaseHelper.TABLE_INFO + " WHERE Name = ?", new String[]{String.valueOf(name)}, null); 

     if (c != null) { 
      c.moveToFirst(); 
     } 
     return c; 
    } 
} 

logcat的錯誤

Caused by: java.lang.IllegalArgumentException: column '_id' does not exist 
      at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:333) 
      at android.widget.CursorAdapter.init(CursorAdapter.java:180) 
      at android.widget.CursorAdapter.<init>(CursorAdapter.java:157) 
      at android.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:96) 
      at android.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:104) 
      at com.example.project.project.ListDisplay.BuildList(ListDisplay.java:49) 
      at com.example.project.project.ListDisplay.onCreate(ListDisplay.java:31) 
      at android.app.Activity.performCreate(Activity.java:6237) 
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
            at android.app.ActivityThread.-wrap11(ActivityThread.java) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 

Answer 1

創建表的查詢仍然使用「ID」（硬編碼字符串）

public void onCreate(SQLiteDatabase db) { 
    db.execSQL("create table " + TABLE_INFO + " (" + ID + " INTEGER PRIMARY KEY ,Name TEXT,Weather TEXT, Date DATETIME, Status Text, TimeIn_Info DATE TIME, TimeOut_Info DATETIME)"); 
    db.execSQL("create table " + TABLE_WORKFORCE + " (" + ID + " INTEGER PRIMARY KEY ,Subcontractors TEXT,NumberOfPerson INTEGER,NumberOfHours TEXT, TInfo_id INTEGER, FOREIGN KEY(TInfo_id) REFERENCES "+TABLE_INFO+"(ID))"); 
} 

你將不得不迫使你的分貝要麼卸載完全地從應用程序的升級您的設備，然後重新安裝或增加VERSION。

SimpleCursorAdapter想要光標中的_id。將它添加到查詢中，例如

Cursor c=database.rawQuery("SELECT _id, Weather, Date, Status, TimeIn_Info, TimeOut_Info FROM " + MyDatabaseHelper.TABLE_INFO + " WHERE Name = ?", new String[]{String.valueOf(name)}, null); 

Answer 2

您需要卸載應用程序以在將ID更改爲_id後重新安裝。您也可以重寫OnUpgrade方法，該方法是SQLiteOpenHelper類下的helper方法，通過向數據庫提供不同的版本號來升級數據庫，然後刪除舊數據庫版本。這可確保您在每次數據庫發生更改時都不必重新安裝應用程序。

你可以使用下面的代碼sinnipet。

@Override 
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
      Log.w(TAG, "Upgrading database from version " + oldVersion + " to " 
        + newVersion + ", which will destroy all old data"); 
      db.execSQL("DROP TABLE IF EXISTS donotes"); 
      //Create the data base with the New Data 
      onCreate(db); 
     } 

使用這樣的：

public void onCreate(SQLiteDatabase db) { 
     db.execSQL("create table " + TABLE_INFO + "(ID INTEGER PRIMARY KEY ,Name TEXT,Weather TEXT, Date DATETIME, Status Text, TimeIn_Info DATE TIME, TimeOut_Info DATETIME);"); 
     db.execSQL("create table " + TABLE_WORKFORCE + "(ID INTEGER PRIMARY KEY ,Subcontractors TEXT,NumberOfPerson INTEGER,NumberOfHours TEXT, TInfo_id INTEGER, FOREIGN KEY(TInfo_id) REFERENCES "+TABLE_INFO+"(ID));"); 

}