Question

My name is Michael, and I am writing an android application that will serve as a very basic class schedule app. So far, I have been able to write the program so that I am able to create and add new classes to the database, however I cannot seem to figure out how to remove a selected entry from the database. The button that saves the entries is defined as follows:

<Button
        android:id="@+id/save"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Save" />

and the listener that it activates is:

private View.OnClickListener onSave=new View.OnClickListener() {
        public void onClick(View v) {
            String type=null;

            switch (types.getCheckedRadioButtonId()) {
                case R.id.math:
                    type="math";
                    break;
                case R.id.cs:
                    type="cs";
                    break;
                case R.id.pe:
                    type="pe";
                    break;
                case R.id.elective:
                    type="elective";
                    break;
            }

            if (restaurantId==null) {
                helper.insert(name.getText().toString(),
                                            address.getText().toString(), type,
                                            notes.getText().toString());
            }
            else {
                helper.update(restaurantId, name.getText().toString(),
                                            address.getText().toString(), type,
                                            notes.getText().toString());
            }

            finish();
        }
    };

Where the ‘insert()’ method is the function in my helper class that adds the entry.

The specific problem is that I am having trouble writing the ‘remove()’ function in the helper class. I have tried using the getWritableDatabase.delete() function, however I am having trouble finding the right parameters. Any point in the right direction would be a big help to me. Thank you in advance.

If it helps at all, this is the insert() function:

public void insert(String name, String address,
            String type, String notes) {
        ContentValues cv=new ContentValues();

        cv.put("name", name);
        cv.put("address", address);
        cv.put("type", type);
        cv.put("notes", notes);

        getWritableDatabase().insert("restaurants", "name", cv);
    }

Answer 1

Are you interested in something like this?

public void deleteValue(String value)
    {
         SQLiteDatabase db = getWritableDatabase();

         String whereClause = "name"+"=?";
         String[]whereArgs = new String[] {String.valueOf(value)};
          db.delete(TABLE_NAME, whereClause, whereArgs);
          db.close();
          Log.v("done","deleted  row ");
    }

Here the parameter value for the deleteValue() is the one on which basis we are willing to delete a row (like delete rows based on the name) so we are using it as where clause.

see the lines

String whereClause = "name"+"=?";
             String[]whereArgs = new String[] {String.valueOf(value)};

This can be assumed as delete statement with where clause as where name = value;