This is a short session in psql using my "books and authors" database.
It illustrates a few basic SQL search techniques. Read the queries, guess
what the answer should be, and try to figure out what all the portions
of the query do.

jondich=> \dt
            List of relations
 Schema |     Name      | Type  |  Owner  
--------+---------------+-------+---------
 public | authors       | table | jondich
 public | books         | table | jondich
 public | books_authors | table | jondich
(3 rows)

jondich=> SELECT * FROM authors;
 id | last_name | first_name | birth_year | death_year 
----+-----------+------------+------------+------------
  1 | Melville  | Herman     |       1819 |       1891
  2 | Austen    | Jane       |       1775 |       1817
  3 | Christie  | Agatha     |       1890 |       1976
  4 | Rushdie   | Salman     |       1947 |          0
  5 | Morrison  | Toni       |       1931 |          0
  6 | Wodehouse | P.G.       |       1881 |       1975
  7 | Gaiman    | Neil       |       1960 |          0
  8 | Pratchett | Terry      |       1948 |       2015
  9 | Willis    | Connie     |       1945 |          0
 10 | Lewis     | Sinclair   |       1885 |          0
(10 rows)

jondich=> SELECT * FROM books;
 id |            title             | publication_year 
----+------------------------------+------------------
  1 | Moby Dick                    |             1851
  2 | Omoo                         |             1847
  3 | Beloved                      |             1987
  4 | Sula                         |             1973
  5 | Midnight's Children          |             1981
  6 | The Satanic Verses           |             1988
  7 | Emma                         |             1815
  8 | Pride and Prejudice          |             1813
  9 | Sense and Sensibility        |             1813
 10 | Right Ho, Jeeves             |             1934
 11 | Leave it to Psmith           |             1923
 12 | The Code of the Woosters     |             1938
 13 | Murder on the Orient Express |             1934
 14 | And Then There Were None     |             1939
 15 | Good Omens                   |             1990
 16 | Neverwhere                   |             1996
 17 | Thief of Time                |             1996
 18 | To Say Nothing of the Dog    |             1997
 19 | Blackout                     |             2010
 20 | All Clear                    |             2010
 21 | Main Street                  |             1920
 22 | Elmer Gantry                 |             1927
(22 rows)

jondich=> SELECT * FROM books_authors;
 book_id | author_id 
---------+-----------
       1 |         1
       2 |         1
       3 |         5
       4 |         5
       5 |         4
       6 |         4
       7 |         2
       8 |         2
       9 |         2
      10 |         6
      11 |         6
      12 |         6
      13 |         3
      14 |         3
      15 |         7
      15 |         8
      16 |         7
      17 |         8
      18 |         9
      19 |         9
      20 |         9
      21 |        10
      22 |        10
(23 rows)

jondich=> SELECT * FROM authors WHERE birth_year > 1930;
 id | last_name | first_name | birth_year | death_year 
----+-----------+------------+------------+------------
  4 | Rushdie   | Salman     |       1947 |          0
  5 | Morrison  | Toni       |       1931 |          0
  7 | Gaiman    | Neil       |       1960 |          0
  8 | Pratchett | Terry      |       1948 |       2015
  9 | Willis    | Connie     |       1945 |          0
(5 rows)

jondich=> SELECT count(*) FROM authors;
 count 
-------
    10
(1 row)

jondich=> SELECT first_name, last_name, birth_year
jondich-> FROM authors
jondich-> WHERE birth_year > 1850
jondich-> ORDER BY birth_year;
 first_name | last_name | birth_year 
------------+-----------+------------
 P.G.       | Wodehouse |       1881
 Sinclair   | Lewis     |       1885
 Agatha     | Christie  |       1890
 Toni       | Morrison  |       1931
 Connie     | Willis    |       1945
 Salman     | Rushdie   |       1947
 Terry      | Pratchett |       1948
 Neil       | Gaiman    |       1960
(8 rows)

jondich=> SELECT authors.last_name, books.title, books.publication_year
jondich-> FROM authors, books, books_authors
jondich-> WHERE authors.id = books_authors.author_id
jondich-> AND books.id = books_authors.book_id
jondich-> ORDER BY last_name, publication_year;
 last_name |            title             | publication_year 
-----------+------------------------------+------------------
 Austen    | Sense and Sensibility        |             1813
 Austen    | Pride and Prejudice          |             1813
 Austen    | Emma                         |             1815
 Christie  | Murder on the Orient Express |             1934
 Christie  | And Then There Were None     |             1939
 Gaiman    | Good Omens                   |             1990
 Gaiman    | Neverwhere                   |             1996
 Lewis     | Main Street                  |             1920
 Lewis     | Elmer Gantry                 |             1927
 Melville  | Omoo                         |             1847
 Melville  | Moby Dick                    |             1851
 Morrison  | Sula                         |             1973
 Morrison  | Beloved                      |             1987
 Pratchett | Good Omens                   |             1990
 Pratchett | Thief of Time                |             1996
 Rushdie   | Midnight's Children          |             1981
 Rushdie   | The Satanic Verses           |             1988
 Willis    | To Say Nothing of the Dog    |             1997
 Willis    | Blackout                     |             2010
 Willis    | All Clear                    |             2010
 Wodehouse | Leave it to Psmith           |             1923
 Wodehouse | Right Ho, Jeeves             |             1934
 Wodehouse | The Code of the Woosters     |             1938
(23 rows)

jondich=>