/* Given the following database schema: */
CREATE TABLE current
(
    ballotpedia_id      TEXT,
    bioguide_id         TEXT,
    birthday_bio        DATE,
    cspan_id            REAL,
    fec_id              TEXT,
    first_name          TEXT,
    gender_bio          TEXT,
    google_entity_id_id TEXT,
    govtrack_id         INTEGER,
    house_history_id    REAL,
    icpsr_id            REAL,
    last_name           TEXT,
    lis_id              TEXT,
    maplight_id         REAL,
    middle_name         TEXT,
    nickname_name       TEXT,
    official_full_name  TEXT,
    opensecrets_id      TEXT,
    religion_bio        TEXT,
    suffix_name         TEXT,
    thomas_id           INTEGER,
    votesmart_id        REAL,
    wikidata_id         TEXT,
    wikipedia_id        TEXT,
        primary key (bioguide_id, cspan_id)
)

CREATE TABLE "current-terms"
(
    address            TEXT,
    bioguide           TEXT,
    caucus             TEXT,
    chamber            TEXT,
    class              REAL,
    contact_form       TEXT,
    district           REAL,
    end                TEXT,
    fax                TEXT,
    last               TEXT,
    name               TEXT,
    office             TEXT,
    party              TEXT,
    party_affiliations TEXT,
    phone              TEXT,
    relation           TEXT,
    rss_url            TEXT,
    start              TEXT,
    state              TEXT,
    state_rank         TEXT,
    title              TEXT,
    type               TEXT,
    url                TEXT,
    primary key (bioguide, end),
    foreign key (bioguide) references current(bioguide_id)
)

CREATE TABLE historical
(
    ballotpedia_id             TEXT,
    bioguide_id                TEXT
            primary key,
    bioguide_previous_id       TEXT,
    birthday_bio               TEXT,
    cspan_id                   TEXT,
    fec_id                     TEXT,
    first_name                 TEXT,
    gender_bio                 TEXT,
    google_entity_id_id        TEXT,
    govtrack_id                INTEGER,
    house_history_alternate_id TEXT,
    house_history_id           REAL,
    icpsr_id                   REAL,
    last_name                  TEXT,
    lis_id                     TEXT,
    maplight_id                TEXT,
    middle_name                TEXT,
    nickname_name              TEXT,
    official_full_name         TEXT,
    opensecrets_id             TEXT,
    religion_bio               TEXT,
    suffix_name                TEXT,
    thomas_id                  TEXT,
    votesmart_id               TEXT,
    wikidata_id                TEXT,
    wikipedia_id               TEXT
)

CREATE TABLE "historical-terms"
(
    address            TEXT,
    bioguide           TEXT
            primary key,
    chamber            TEXT,
    class              REAL,
    contact_form       TEXT,
    district           REAL,
    end                TEXT,
    fax                TEXT,
    last               TEXT,
    middle             TEXT,
    name               TEXT,
    office             TEXT,
    party              TEXT,
    party_affiliations TEXT,
    phone              TEXT,
    relation           TEXT,
    rss_url            TEXT,
    start              TEXT,
    state              TEXT,
    state_rank         TEXT,
    title              TEXT,
    type               TEXT,
    url                TEXT,
    foreign key (bioguide) references historical(bioguide_id)
)

CREATE TABLE "social-media"
(
    bioguide     TEXT
            primary key,
    facebook     TEXT,
    facebook_id  REAL,
    govtrack     REAL,
    instagram    TEXT,
    instagram_id REAL,
    thomas       INTEGER,
    twitter      TEXT,
    twitter_id   REAL,
    youtube      TEXT,
    youtube_id   TEXT,
    foreign key (bioguide) references current(bioguide_id)
)

/* Answer the following: Please list the username of the current official Facebook presence of all the current legislators that are famous or impact. username of the current official Facebook presence of the legislators refers to facebook; legislators that are famous or impact refers to wikipedia_id is not null; */
SELECT 
SELECT T2.facebook FROM current AS T1 INNER JOIN `social-media` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T1.wikipedia_id IS NOT NULL GROUP BY T2.facebook