def add_data(conn, mnemonic, data):
    """Add data of a specific mnemonic to database if it not exists
    Parameters
    ----------
    conn : DBobject
        connection object to access database
    mnemonic : string
        identifies the table
    data : list
        specifies the data
    """
    c = conn.cursor()
    c.execute('SELECT id from {} WHERE start_time= {}'.format(mnemonic,
        data[0]))
    temp = c.fetchall()
    if len(temp) == 0:
        c.execute(
            'INSERT INTO {} (start_time,end_time,data_points,average,deviation)                 VALUES (?,?,?,?,?)'
            .format(mnemonic), data)
        conn.commit()
    else:
        print('data for {} already exists'.format(mnemonic))
