如何从Android的表中删除sqlite中的所有logging？
我的应用程序有两个button，第一个button用于删除用户inputlogging，第二个button用于删除所有logging。 但是，当我想删除数据显示消息
“你的申请已被强制停止”。
请检查我的代码，并给我一些build议。
public void deleteAll() { //SQLiteDatabase db = this.getWritableDatabase(); // db.delete(TABLE_NAME,null,null); //db.execSQL("delete * from"+ TABLE_NAME); db.execSQL("TRUNCATE table" + TABLE_NAME); db.close(); } 和
public void delete(String id) { String[] args={id}; getWritableDatabase().delete("texts", "_ID=?", args); }
但它显示以下日志猫错误。
03-07 15:57:07.143: ERROR/AndroidRuntime(287): Uncaught handler: thread main exiting due to uncaught exception 03-07 15:57:07.153: ERROR/AndroidRuntime(287): java.lang.NullPointerException 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.example.MySQLiteHelper.delete(MySQLiteHelper.java:163) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.example.Settings$4.onClick(Settings.java:94) -07 15:57:07.153: ERROR/AndroidRuntime(287): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:158) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at android.os.Handler.dispatchMessage(Handler.java:99) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at android.os.Looper.loop(Looper.java:123) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at android.app.ActivityThread.main(ActivityThread.java:4203) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at java.lang.reflect.Method.invokeNative(Native Method) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at java.lang.reflect.Method.invoke(Method.java:521) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) 03-07 15:57:07.153: ERROR/AndroidRuntime(287): at dalvik.system.NativeStart.main(Native Method)
你错过了一个空间： db.execSQL("delete * from " + TABLE_NAME);
也没有必要甚至包括* ，最好是使用：
db.execSQL("delete from "+ TABLE_NAME);
db.delete(TABLE_NAME, null, null);
或者，如果您希望函数返回已删除行的计数 ，
db.delete(TABLE_NAME, "1", null);
从SQLiteDatabase 删除方法的文档：
要删除所有行并获得一个计数传递“1”作为whereClause。
要删除表格中的所有行，您可以使用：
db.delete(TABLE_NAME, null, null);
没有必要使用“执行”function。下面的代码为我工作:::
db.delete(TABLE_NAME,null,null); db.close();
SQLite不支持TRUNCATE命令。 您应该使用您在上一行中尝试过的内容：
DELETE FROM `TABLE_NAME`;
PS可以通过对给定数据库的所有查询使用相同的数据库连接实例来优化程序，而不是为每个查询创build一个新的查询。
SQLiteDatabase db = this.getWritableDatabase(); db.execSQL("DELETE FROM tablename"); //delete all rows in a table db.close();
这个工作对我来说:)
试试这个代码从表中删除所有的数据..
String selectQuery = "DELETE FROM table_name "; Cursor cursor = data1.getReadableDatabase().rawQuery(selectQuery, null);
用最后两个空参数使用Sqlit删除函数。
db.delete(TABLE_NAME,null,null)
我用这个类来处理数据库，希望将来可以帮到一些。
快乐的编码。
public class Database { private static class DBHelper extends SQLiteOpenHelper { /** * Database name */ private static final String DB_NAME = "db_name"; /** * Table Names */ public static final String TABLE_CART = "DB_CART"; /** * Cart Table Columns */ public static final String CART_ID_PK = "_id";// Primary key public static final String CART_DISH_NAME = "dish_name"; public static final String CART_DISH_ID = "menu_item_id"; public static final String CART_DISH_QTY = "dish_qty"; public static final String CART_DISH_PRICE = "dish_price"; /** * String to create reservation tabs table */ private final String CREATE_TABLE_CART = "CREATE TABLE IF NOT EXISTS " + TABLE_CART + " ( " + CART_ID_PK + " INTEGER PRIMARY KEY, " + CART_DISH_NAME + " TEXT , " + CART_DISH_ID + " TEXT , " + CART_DISH_QTY + " TEXT , " + CART_DISH_PRICE + " TEXT);"; public DBHelper(Context context) { super(context, DB_NAME, null, 2); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(CREATE_TABLE_CART); } @Override public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) { db.execSQL("DROP TABLE IF EXISTS " + CREATE_TABLE_CART); onCreate(db); } } /** * CART handler */ public static class Cart { /** * Check if Cart is available or not * * @param context * @return */ public static boolean isCartAvailable(Context context) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); boolean exists = false; try { String query = "SELECT * FROM " + DBHelper.TABLE_CART; Cursor cursor = db.rawQuery(query, null); exists = (cursor.getCount() > 0); cursor.close(); db.close(); } catch (SQLiteException e) { db.close(); } return exists; } /** * Insert values in cart table * * @param context * @param dishName * @param dishPrice * @param dishQty * @return */ public static boolean insertItem(Context context, String itemId, String dishName, String dishPrice, String dishQty) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getWritableDatabase(); ContentValues values = new ContentValues(); values.put(DBHelper.CART_DISH_ID, "" + itemId); values.put(DBHelper.CART_DISH_NAME, "" + dishName); values.put(DBHelper.CART_DISH_PRICE, "" + dishPrice); values.put(DBHelper.CART_DISH_QTY, "" + dishQty); try { db.insert(DBHelper.TABLE_CART, null, values); db.close(); return true; } catch (SQLiteException e) { db.close(); return false; } } /** * Check for specific record by name * * @param context * @param dishName * @return */ public static boolean isItemAvailable(Context context, String dishName) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); boolean exists = false; String query = "SELECT * FROM " + DBHelper.TABLE_CART + " WHERE " + DBHelper.CART_DISH_NAME + " = '" + String.valueOf(dishName) + "'"; try { Cursor cursor = db.rawQuery(query, null); exists = (cursor.getCount() > 0); cursor.close(); } catch (SQLiteException e) { e.printStackTrace(); db.close(); } return exists; } /** * Update cart item by item name * * @param context * @param dishName * @param dishPrice * @param dishQty * @return */ public static boolean updateItem(Context context, String itemId, String dishName, String dishPrice, String dishQty) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getWritableDatabase(); ContentValues values = new ContentValues(); values.put(DBHelper.CART_DISH_ID, itemId); values.put(DBHelper.CART_DISH_NAME, dishName); values.put(DBHelper.CART_DISH_PRICE, dishPrice); values.put(DBHelper.CART_DISH_QTY, dishQty); try { String[] args = new String[]{dishName}; db.update(DBHelper.TABLE_CART, values, DBHelper.CART_DISH_NAME + "=?", args); db.close(); return true; } catch (SQLiteException e) { db.close(); return false; } } /** * Get cart list * * @param context * @return */ public static ArrayList<CartModel> getCartList(Context context) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); ArrayList<CartModel> cartList = new ArrayList<>(); try { String query = "SELECT * FROM " + DBHelper.TABLE_CART + ";"; Cursor cursor = db.rawQuery(query, null); for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) { cartList.add(new CartModel( cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_ID)), cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_NAME)), cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_QTY)), Integer.parseInt(cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_PRICE))) )); } db.close(); } catch (SQLiteException e) { db.close(); } return cartList; } /** * Get total amount of cart items * * @param context * @return */ public static String getTotalAmount(Context context) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); double totalAmount = 0.0; try { String query = "SELECT * FROM " + DBHelper.TABLE_CART + ";"; Cursor cursor = db.rawQuery(query, null); for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) { totalAmount = totalAmount + Double.parseDouble(cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_PRICE))) * Double.parseDouble(cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_QTY))); } db.close(); } catch (SQLiteException e) { db.close(); } if (totalAmount == 0.0) return ""; else return "" + totalAmount; } /** * Get item quantity * * @param context * @param dishName * @return */ public static String getItemQty(Context context, String dishName) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); Cursor cursor = null; String query = "SELECT * FROM " + DBHelper.TABLE_CART + " WHERE " + DBHelper.CART_DISH_NAME + " = '" + dishName + "';"; String quantity = "0"; try { cursor = db.rawQuery(query, null); if (cursor.getCount() > 0) { cursor.moveToFirst(); quantity = cursor.getString(cursor .getColumnIndex(DBHelper.CART_DISH_QTY)); return quantity; } } catch (SQLiteException e) { e.printStackTrace(); } return quantity; } /** * Delete cart item by name * * @param context * @param dishName */ public static void deleteCartItem(Context context, String dishName) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); try { String[] args = new String[]{dishName}; db.delete(DBHelper.TABLE_CART, DBHelper.CART_DISH_NAME + "=?", args); db.close(); } catch (SQLiteException e) { db.close(); e.printStackTrace(); } } }//End of cart class /** * Delete database table * * @param context */ public static void deleteCart(Context context) { DBHelper dbHelper = new DBHelper(context); SQLiteDatabase db = dbHelper.getReadableDatabase(); try { db.execSQL("DELETE FROM " + DBHelper.TABLE_CART); } catch (SQLiteException e) { e.printStackTrace(); } }
}
用法：
if(Database.Cart.isCartAvailable(context)){ Database.deleteCart(context); }
getContentResolver().delete(DB.TableName.CONTENT_URI, null, null);
写吧
SQLiteDatabase db = this.getWritableDatabase(); db.execSQL("delete from "+TableName);
可以是有用的。
public boolean deleteAllFood() { SQLiteDatabase db = dbHelper.getReadableDatabase(); int affectedRows = db.delete(DBHelper.TABLE_NAME_FOOD, null, null); return affectedRows > 0; } public class DBProgram { private static DBProgram INSTANCE; private Context context; private DBHelper dbHelper; private DBProgram(Context context) { // burda bu methodu kullanan activity ile eileştiriyoruz this.dbHelper = new DBHelper(context); } public static synchronized DBProgram getInstance(Context context) { if (INSTANCE == null) { INSTANCE = new DBProgram(context); } return INSTANCE; } //********************************************** public boolean updateById(ProgramModel program) { SQLiteDatabase database = dbHelper.getWritableDatabase(); ContentValues contentValues = new ContentValues(); contentValues.put(DBHelper.COLUM_NAME_P, program.getProgName()); contentValues.put(DBHelper.COLUM_DAY_P, program.getDay()); contentValues.put(DBHelper.COLUMN_WEIGHT_P, program.getWeight()); contentValues.put(DBHelper.COLUMN_SET_P, program.getSet()); contentValues.put(DBHelper.COLUMN_REPETITION_P, program.getRepetition()); int affectedRows = database.update(DBHelper.TABLE_NAME_PROGRAM, contentValues, "PROG_ID_P = ?", new String[]{String.valueOf(program.getId())}); return affectedRows > 0; } //********************************************** //********************************************** // TODO public boolean deleteProgramById(int id) { SQLiteDatabase database = dbHelper.getReadableDatabase(); int affectedRows = database.delete(DBHelper.TABLE_NAME_PROGRAM, DBHelper.COLUMN_ID_P + "= ?", new String[]{String.valueOf(id)}); // return bize etkilenen sıra sayısınıını temsil eder return affectedRows > 0; } //********************************************** //*************************************************** public boolean deleteProgramByName(String progName) { SQLiteDatabase database = dbHelper.getReadableDatabase(); final String whereClause = DBHelper.COLUM_NAME_P + "=?"; final String whereArgs[] = {progName}; int affectedRows = database.delete(DBHelper.TABLE_NAME_PROGRAM, whereClause, whereArgs); return affectedRows > 0; } //*************************************************** //************************************** get Meal // TODO WEB Get All Meals public List<ProgramModel> getAllProgram(String name) { List<ProgramModel> foodList = new ArrayList<>(); ProgramModel food; SQLiteDatabase database = dbHelper.getReadableDatabase(); final String kolonlar[] = {DBHelper.COLUMN_ID_P, DBHelper.COLUM_NAME_P, DBHelper.COLUM_DAY_P, DBHelper.COLUMN_WEIGHT_P, DBHelper.COLUMN_SET_P, DBHelper.COLUMN_REPETITION_P}; final String whereClause = DBHelper.COLUM_DAY_P + "=?"; final String whereArgs[] = {name}; Cursor cursor = database.query(DBHelper.TABLE_NAME_PROGRAM, kolonlar, whereClause, whereArgs, null, null, null); while (cursor.moveToNext()) { food = new ProgramModel(); food.setId(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_ID_P))); food.setProgName(cursor.getString(cursor.getColumnIndex(DBHelper.COLUM_NAME_P))); food.setDay(cursor.getString(cursor.getColumnIndex(DBHelper.COLUM_DAY_P))); food.setWeight(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_WEIGHT_P))); food.setSet(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_SET_P))); food.setRepetition(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_REPETITION_P))); foodList.add(food); } database.close(); cursor.close(); return foodList; } //************************************** //**************************************insert FOOD //TODO LOCAL insert Foods public boolean insertProgram(ProgramModel favorite) { boolean result = false; ContentValues contentValues = new ContentValues(); contentValues.put(DBHelper.COLUM_NAME_P, favorite.getProgName()); contentValues.put(DBHelper.COLUM_DAY_P, favorite.getDay()); contentValues.put(DBHelper.COLUMN_WEIGHT_P, favorite.getWeight()); contentValues.put(DBHelper.COLUMN_SET_P, favorite.getSet()); contentValues.put(DBHelper.COLUMN_REPETITION_P, favorite.getRepetition()); SQLiteDatabase database = dbHelper.getWritableDatabase(); long id = database.insert(DBHelper.TABLE_NAME_PROGRAM, null, contentValues); if (id != 1) { result = true; } database.close(); return result; } //*************************************************** // ******************************* SQLITE HELPER CLASS ****************** private class DBHelper extends SQLiteOpenHelper { private final Context context; private static final String DATABASE_NAME = "PROGRAM_INFO"; private static final String TABLE_NAME_PROGRAM = "PROGRAM"; private static final int DATABASE_VERSION = 2; // FOOD private static final String COLUMN_ID_P = "PROG_ID_P"; private static final String COLUM_NAME_P = "PROG_NAME_P"; private static final String COLUM_DAY_P = "PROG_DAY_P"; private static final String COLUMN_WEIGHT_P = "PROG_WEIGHT_P"; private static final String COLUMN_SET_P = "PROG_SET_P"; private static final String COLUMN_REPETITION_P = "PROG_REPETITION_P"; private final String CREATE_TABLE_PROGRAM = "CREATE TABLE " + TABLE_NAME_PROGRAM + " (" + COLUMN_ID_P + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUM_NAME_P + " TEXT, " + COLUM_DAY_P + " TEXT, " + COLUMN_WEIGHT_P + " INTEGER, " + COLUMN_SET_P + " INTEGER, " + COLUMN_REPETITION_P + " INTEGER)"; private static final String DROP_TABLE_PROGRAM = "DROP TABLE IF EXIST " + TABLE_NAME_PROGRAM; public DBHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); this.context = context; } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(CREATE_TABLE_PROGRAM); Util.showMessage(context, "Database Created"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL(DROP_TABLE_PROGRAM); Util.showMessage(context, "Database Upgrated"); onCreate(db); } @Override public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) { super.onDowngrade(db, oldVersion, newVersion); } } }
