getWritableDatabase不起作用

Question

我正在爲android應用程序編寫一個函數，它可以通過導入最新的csv文件來更新sqlite數據庫。 當用戶點擊按鈕時，程序應該刪除舊錶並根據最新數據創建另一個新表。該應用程序能夠在第一次按下按鈕時寫入數據。但是，如果數據已經存在，則發現錯誤。

05-09 16:41:34.088: E/SQLiteDatabase(3056): Error inserting order_qty=1                                                                 tran_code=NS item_code=IC559 line_no=1 customer_ref_no="PO# 25192600" order_date=20130221 cust_code=099496 
05-09 16:41:34.088: E/SQLiteDatabase(3056): android.database.sqlite.SQLiteConstraintException: columns order_date, cust_code, item_code, tran_code are not unique (code 19) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(Native Method) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:782) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:788) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1469) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1339) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at test.andftpclient.MainActivity$2.onClick(MainActivity.java:118) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.view.View.performClick(View.java:4438) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.view.View$PerformClick.run(View.java:18422) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.os.Handler.handleCallback(Handler.java:733) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.os.Handler.dispatchMessage(Handler.java:95) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.os.Looper.loop(Looper.java:136) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at java.lang.reflect.Method.invokeNative(Native Method) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at java.lang.reflect.Method.invoke(Method.java:515) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
05-09 16:41:34.088: E/SQLiteDatabase(3056):  at dalvik.system.NativeStart.main(Native Method) 

我知道出現此錯誤的主要原因是，在插入數據具有相同的唯一主鍵現有的數據，但我爲什麼舊錶，則不能刪除不知道。 這裏是我的代碼：

主要活動

public void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main);  



    Button button_import_csv = (Button) findViewById(R.id.button_import); 
    button_import_csv.setOnClickListener(new View.OnClickListener(){ 
     public void onClick(View v){ 


      DatabaseHelper helper = new DatabaseHelper(getApplicationContext()); 
      SQLiteDatabase db = helper.getWritableDatabase(); 


      try{ 

       FileReader file = new FileReader("/sdcard/downloadedfolder/A1/adv_sales_order.csv"); 
       BufferedReader buffer = new BufferedReader(file); 
       ContentValues contentValues=new ContentValues(); 
       String line = ""; 
       String tableName ="adv_sales_order"; 

       db.beginTransaction(); 
       while ((line = buffer.readLine()) != null) { 
        String[] str = line.split("\t"); 


        contentValues.put("order_date", str[0]); 
        contentValues.put("cust_code", str[1]); 
        contentValues.put("customer_ref_no", str[2]); 
        contentValues.put("line_no", str[3]); 
        contentValues.put("item_code", str[4]); 
        contentValues.put("tran_code", str[5]); 
        contentValues.put("order_qty", str[6]); 
        db.insert(tableName, null, contentValues); 

       } 
       db.setTransactionSuccessful(); 
       db.endTransaction(); 
      }catch (IOException e){ 

      } 

      helper.close(); 
     } 
    }); 
} 

}

DatabaseHelper類：

public class DatabaseHelper extends SQLiteOpenHelper { 

private static final String DATABASE_NAME = "icedb.db"; 
private static final int DATABASE_VERSION = 1; 
private static final String TABLE_1 = "adv_sales_order"; 



public DatabaseHelper (Context context) { 
    super(context, DATABASE_NAME, null, DATABASE_VERSION); 
} 

@Override 
public void onCreate(SQLiteDatabase db) { 
    // TODO Auto-generated method stub 

    String CREATE_TB; 

    CREATE_TB = "CREATE TABLE adv_sales_order (" 
      + "order_date text not null, " 
      + "cust_code text not null, " 
      + "customer_ref_no text, " 
      + "line_no integer not null, " 
      + "item_code text not null, " 
      + "tran_code text not null, " 
      + "order_qty real not null, " 
      + "constraint pk_adv_sales_order " 
      + "primary key (order_date, " 
      + "cust_code, " 
      + "item_code, " 
      + "tran_code))"; 
    db.execSQL(CREATE_TB); 


} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    // TODO Auto-generated method stub 

    db.execSQL("DROP TABLE IF EXISTS "+ TABLE_1); 

    onCreate(db); 
} 

public void insert_adv_sales_order (ContentValues values) { 
    SQLiteDatabase db = getWritableDatabase(); 
    db.insert("adv_sales_order", null, values); 
    db.close(); 
} 

}

誰能給我一些提示嗎？謝謝。

Answer 1

我想你誤解了onCreate和onUpdate的使用。 onCreate被稱爲，並非每次您撥打getWriteableDatabase，但您隨時撥打getWriteableDatabase,時數據庫尚不存在。同樣，當現有數據庫中的版本號與代碼中的版本號不匹配時，將調用onUpdate。

爲了刪除表格，在給定代碼的情況下，我們可以將onUpdate明確地稱爲函數insert_adv_sales_order的第二行。

Answer 2

android.database.sqlite.SQLiteConstraintException: 
columns order_date, cust_code, item_code, tran_code are not unique (code 19) 

在你創建表的語句中，你有這樣的：

"primary key (order_date, cust_code, item_code, tran_code))"; 

這意味着你的主鍵是第四列值的組合。每個記錄必須具有這些值的唯一組合。無論您插入什麼值，看起來都不是這樣。