input: Write a function to select all rows from a table where the 'status' is 'approved'. This function should execute a SQL query to retrieve the desired rows and return them as a list.
  assert select_approved_rows() == [(1, 'approved'), (3, 'approved')]
  assert select_approved_rows() == []
output: def select_approved_rows():
      import sqlite3
      conn = sqlite3.connect('example.db')
      cursor = conn.cursor()
      cursor.execute("SELECT * FROM table_name WHERE status = 'approved'")
      rows = cursor.fetchall()
      conn.close()
      return rows