Among the professors with more than average teaching ability, list the full name and email address of the professors who advise two or more students.
more than average teaching ability refers to teachingability > AVG(teachingability); full_name of the professor = first_name, last_name; email address of the professor refers to email; advises two or more students refers to COUNT(student_id) > = 2;

SELECT T2.first_name, T2.last_name, T2.email FROM RA AS T1 INNER JOIN prof AS T2 ON T1.prof_id = T2.prof_id WHERE T2.teachingability > ( SELECT AVG(teachingability) FROM prof ) GROUP BY T2.prof_id HAVING COUNT(T1.student_id) >= 2
CREATE TABLE IF NOT EXISTS "course"
(
    course_id INTEGER
        constraint course_pk
            primary key,
    name      TEXT,
    credit    INTEGER,
    diff      INTEGER
);
CREATE TABLE prof
(
    prof_id         INTEGER
        constraint prof_pk
            primary key,
    gender          TEXT,
    first_name      TEXT,
    last_name       TEXT,
    email           TEXT,
    popularity      INTEGER,
    teachingability INTEGER,
    graduate_from   TEXT
);
CREATE TABLE RA
(
    student_id INTEGER,
    capability INTEGER,
    prof_id    INTEGER,
    salary     TEXT,
    primary key (student_id, prof_id),
    foreign key (prof_id) references prof(prof_id),
    foreign key (student_id) references student(student_id)
);
CREATE TABLE registration
(
    course_id  INTEGER,
    student_id INTEGER,
    grade      TEXT,
    sat        INTEGER,
    primary key (course_id, student_id),
    foreign key (course_id) references course(course_id),
    foreign key (student_id) references student(student_id)
);
CREATE TABLE student
(
    student_id   INTEGER
            primary key,
    f_name       TEXT,
    l_name       TEXT,
    phone_number TEXT,
    email        TEXT,
    intelligence INTEGER,
    gpa          REAL,
    type         TEXT
);
