getting row id from sqlite using other fields as where condition

Question

sir, how can i return the rowid of my database depending on the inputs name, number? this code just return the value 0 everytime. my primary key is KEY_ROWID. thanks for help in advance

//get rowid
public long getRowId(String name, String number) 
{
    // TODO Auto-generated method stub
    String[] columns = new String[]{KEY_ROWID, KEY_NAME, KEY_NUMBER};
    Cursor c = ourDatabase.query(DATABASE_TABLE, columns, KEY_NUMBER+ "=" +number, null, null, null, null);

    long rowid = c.getColumnIndex(KEY_ROWID);
    return rowid;
}

here is how i access it

public void onClick(View arg0) {
            nameChanged = sqlName.getText().toString();
            numChanged = sqlNumber.getText().toString();
            GroupDb info = new GroupDb(EditDetails.this);
            info.open();
            long rowid = info.getRowId(name, num);
            info.updateNameNumber(rowid, nameChanged, numChanged);
            Toast.makeText(getApplicationContext(), rowid+" "+nameChanged+" "+numChanged, Toast.LENGTH_LONG).show();
            ArrayList<Contact> searchResults = info.getView();
            MyCustomBaseAdapter mcba = new MyCustomBaseAdapter(EditDetails.this, searchResults);
            mcba.updateResults(searchResults);
            Toast.makeText(getApplicationContext(), "Update Successful!", Toast.LENGTH_LONG).show();
            info.close();
            }
        });

Answer 1

From the fine manual:

public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)
[...]
Returns

A Cursor object, which is positioned before the first entry.

So first you have step c into the result set and you can use moveToFirst for that:

c.moveToFirst();

Now you need to extract the rowid from the row that the cursor is pointing at. But getColumnIndex is for mapping a column name to a position in the row:

Returns the zero-based index for the given column name, or -1 if the column doesn't exist.

You're getting a zero from getColumnIndex because your KEY_ROWID is the first column in your SELECT query.

I think you're looking for getLong if you want to extract a long from the Cursor's result set:

long rowid = c.getLong(c.getColumnIndex(KEY_ROWID));

If you know the structure of your query (which you do), you could skip the getColumnIndex call and just use the known index:

long rowid = c.getLong(0);

And if all you're doing is looking up the rowid, you can SELECT just KEY_ROWID:

String[] columns = new String[]{KEY_ROWID};

There's no need to pull things out of the database that you're ignoring.