Android SQLite：更新语句

我需要在我的应用程序中实现SQLite。 我遵循这个教程。 在Android中创build和使用数据库

一切工作正常。 我插入了5行的1行。 现在我只想更新1列的值，其他的将保持不变。

教程中有一个更新方法，但它需要所有的参数，但是我只想更新一列。

Answer 1

您可以使用下面的代码。

String strFilter = "_id=" + Id; ContentValues args = new ContentValues(); args.put(KEY_TITLE, title); myDB.update("titles", args, strFilter, null); 

Answer 2

你可以试试：

 db.execSQL("UPDATE DB_TABLE SET YOUR_COLUMN='newValue' WHERE id=6 "); 

要么

 ContentValues newValues = new ContentValues(); newValues.put("YOUR_COLUMN", "newValue"); db.update("YOUR_TABLE", newValues, "id=6", null); 

要么

 ContentValues newValues = new ContentValues(); newValues.put("YOUR_COLUMN", "newValue"); String[] args = new String[]{"user1", "user2"}; db.update("YOUR_TABLE", newValues, "name=? OR name=?", args); 

Answer 3

这是在教程中如何做到这一点：

  ContentValues args = new ContentValues(); args.put(columnName, newValue); db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null); 

使用ContentValues来设置更新的列，而不是你必须指定的update()方法，表和一个条件只更新你想要更新的行。

Answer 4

你总是可以执行SQL。

 update [your table] set [your column]=value 

例如

 update Foo set Bar=125 

Answer 5

SQLiteDatabase对象取决于数据库上的操作types。

更多信息请访问官方网站：

https://developer.android.com/training/basics/data-storage/databases.html#UpdateDbRow

它解释了如何操作SQLite数据库的咨询。

插入行

以写入模式获取数据存储库

 SQLiteDatabase db = mDbHelper.getWritableDatabase(); 

创build一个新的值的映射，其中列名是键

 ContentValues values = new ContentValues(); values.put(FeedEntry.COLUMN_NAME_ENTRY_ID, id); values.put(FeedEntry.COLUMN_NAME_TITLE, title); values.put(FeedEntry.COLUMN_NAME_CONTENT, content); 

插入新行，返回新行的主键值

 long newRowId; newRowId = db.insert( FeedEntry.TABLE_NAME, FeedEntry.COLUMN_NAME_NULLABLE, values); 

更新行

定义“where”部分的查询。

 String selection = FeedEntry.COLUMN_NAME_ENTRY_ID + " LIKE ?"; 

以占位符顺序指定参数。

 String[] selectionArgs = { String.valueOf(rowId) }; SQLiteDatabase db = mDbHelper.getReadableDatabase(); 

一列的新值

 ContentValues values = new ContentValues(); values.put(FeedEntry.COLUMN_NAME_TITLE, title); 

根据ID更新哪一行

 String selection = FeedEntry.COLUMN_NAME_ENTRY_ID + " LIKE ?"; String[] selectionArgs = { String.valueOf(rowId) }; int count = db.update( FeedReaderDbHelper.FeedEntry.TABLE_NAME, values, selection, selectionArgs); 

Answer 6

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); }