Android SQLite: 更新语句

you can always execute SQL.

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

for example

update Foo set Bar=125

It's all in the tutorial how to do that:

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

Use ContentValues to set the updated columns and than the update() method in which you have to specifiy, the table and a criteria to only update the rows you want to update.

You can use the code below.

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

You can try:

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

Or

ContentValues newValues = new ContentValues();
newValues.put("YOUR_COLUMN", "newValue");


db.update("YOUR_TABLE", newValues, "id=6", null);

Or

ContentValues newValues = new ContentValues();
newValues.put("YOUR_COLUMN", "newValue");


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

The SQLiteDatabase object depends on the type of operation on the database.

More information, visit the official website:

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

It explains how to manipulate consultations on the SQLite database.

INSERT ROW

Gets the data repository in write mode

SQLiteDatabase db = mDbHelper.getWritableDatabase();

Create a new map of values, where column names are the keys

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);

Insert the new row, returning the primary key value of the new row

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

UPDATE ROW

Define 'where' part of query.

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

Specify arguments in placeholder order.

String[] selectionArgs = { String.valueOf(rowId) };




SQLiteDatabase db = mDbHelper.getReadableDatabase();

New value for one column

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

Which row to update, based on the ID

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

I use this class to handle database.I hope it will help some one in future.

Happy coding.

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();
}


}

}

Usage:

  if(Database.Cart.isCartAvailable(context)){


Database.deleteCart(context);


}