Question

I’m trying to write three different methods for inserting, updating and deleting data in SQLite Database in Android. So far I can insert data in the database, but I can’t understand how to add the where clause in SQL.
Here is the code I’m using :

The update methods:

public boolean updateSQL(String tableName,String key,String value){
    return updateData(tableName,key,value);
}

private static boolean updateData(String tableName,String key,String value){
    sqliteDb = instance.getWritableDatabase();
    String where = "id=?";
    ContentValues values = new ContentValues();
    values.put(key, value);
    values.put(key, value);
    sqliteDb.update(tableName, values, where, null);
    return true;
}

… and I’m invoking this method like this:

dbHelper.updateSQL("saved_codes", "code_id", "3");
//dbHelper is an instance to a custom DatabaseHelper class.

.. and the delete methods:

public boolean deleteSQL(String tableName,String key,String value){
    return deleteData(tableName,key,value);
}

private static boolean deleteData(String tableName,String key,String value) {
    sqliteDb = instance.getWritableDatabase();
    ContentValues values = new ContentValues();
    String where = null;
    String[] whereArgs = null;
    values.put(key, value);
    values.put(key, value);
    sqliteDb.delete(tableName, where, whereArgs);
    return true;
}

I know that the Strings where and whereArgs are null, but actually I can’t understand how to add them.
I don’t expect someone to write the code for me, but some good advice, suggestions or even samples from the internet are welcome.

Answer 1

You need whereArgs for

String where = "id=?";

something like :

sqliteDb.update(tableName, values, where, new String[] {"42"});

where 42 would be the _id of the row to update. Also prefer BaseColumns._ID to “id”.