When did the staff member named Janessa Sawayn join the company?
CREATE TABLE vehicles (
    vehicle_id number,
    vehicle_details text
)

CREATE TABLE lessons (
    lesson_id number,
    customer_id number,
    lesson_status_code text,
    staff_id number,
    vehicle_id number,
    lesson_date time,
    lesson_time text,
    price number
)

CREATE TABLE staff (
    staff_id number,
    staff_address_id number,
    nickname text,
    first_name text,
    middle_name text,
    last_name text,
    date_of_birth time,
    date_joined_staff time,
    date_left_staff time
)

CREATE TABLE addresses (
    address_id number,
    line_1_number_building text,
    city text,
    zip_postcode text,
    state_province_county text,
    country text
)

CREATE TABLE customers (
    customer_id number,
    customer_address_id number,
    customer_status_code text,
    date_became_customer time,
    date_of_birth time,
    first_name text,
    last_name text,
    amount_outstanding number,
    email_address text,
    phone_number text,
    cell_mobile_phone_number text
)

CREATE TABLE customer_payments (
    customer_id number,
    datetime_payment time,
    payment_method_code text,
    amount_payment number
)
SELECT date_joined_staff FROM staff WHERE first_name = "Janessa" AND last_name = "Sawayn"
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: When did the staff member named Janessa Sawayn join the company? ### Input: CREATE TABLE vehicles (
    vehicle_id number,
    vehicle_details text
)

CREATE TABLE lessons (
    lesson_id number,
    customer_id number,
    lesson_status_code text,
    staff_id number,
    vehicle_id number,
    lesson_date time,
    lesson_time text,
    price number
)

CREATE TABLE staff (
    staff_id number,
    staff_address_id number,
    nickname text,
    first_name text,
    middle_name text,
    last_name text,
    date_of_birth time,
    date_joined_staff time,
    date_left_staff time
)

CREATE TABLE addresses (
    address_id number,
    line_1_number_building text,
    city text,
    zip_postcode text,
    state_province_county text,
    country text
)

CREATE TABLE customers (
    customer_id number,
    customer_address_id number,
    customer_status_code text,
    date_became_customer time,
    date_of_birth time,
    first_name text,
    last_name text,
    amount_outstanding number,
    email_address text,
    phone_number text,
    cell_mobile_phone_number text
)

CREATE TABLE customer_payments (
    customer_id number,
    datetime_payment time,
    payment_method_code text,
    amount_payment number
) ### Response: SELECT date_joined_staff FROM staff WHERE first_name = "Janessa" AND last_name = "Sawayn"