Answers to sql questions.

SQL problems

1. Get all restaurants
Write a query that returns all of the restaurants, with all of the fields.
  SELECT * FROM restaurants;

2. Get Italian restaurants
Write a query that returns all of the Italian restaurants, with all of the fields
  SELECT * FROM restaurants
  WHERE cuisine='Italian';

3. Get 10 Italian restaurants, subset of fields
Write a query that gets 10 Italian restaurants, returning only the id and name fields.
  SELECT id,name FROM restaurants WHERE cuisine='Italian' LIMIT 10;

4. Count of Thai restaurants
Write a query that returns the number of Thai restaurants.
  SELECT COUNT(*) FROM restaurants WHERE cuisine='Thai';

5. Count of restaurants
Write a query that returns the total number of restaurants.
  SELECT COUNT(*) FROM restaurants;

6. Count of Thai restaurants in zip code
Write a query that returns the number of Thai restaurants in the 11372 zip code.
  SELECT * FROM restaurants WHERE cuisine='Thai' AND address_zipcode='11372';

7. Italian restaurants in one of several zip codes
Write a query that returns the id and name of five Italian restaurants in the 10012, 10013, or 10014 zip codes. The initial results (before limiting to five) should be alphabetically sorted.
  SELECT id,name FROM restaurants WHERE cuisine='Italian' AND address_zipcode IN ('10012', '10013', '10014') ORDER BY name LIMIT 5;

8. Create a restaurant
  Create a restaurant with the following properties:

name: 'Byte Cafe',
borough: 'Brooklyn',
cuisine: 'coffee',
address_building_number: '123',
address_street: 'Atlantic Avenue',
address_zipcode: '11231'

  INSERT INTO restaurants (name, etc)
  VALUES ('Byte Cafe', 'etc');

9. Create a restaurant and return id and name
Create a restaurant with values of your choosing, and return the id and name.


10. Create three restaurants and return id and name
Create three restaurants using a single command, with values of your choosing, returning the id and name of each restaurant.
  COPY restaurants (id, name, nyc_restaurant_id, borough, cuisine, address_building_number, address_street, address_zipcode) FROM stdin;
  1	Dj Reynolds Pub And Restaurant	30191841	Manhattan	Irish	351	West   57 Street	10019
  2	Riviera Caterer	40356018	Brooklyn	American 	2780	Stillwell Avenue	11224
  3	Morris Park Bake Shop	30075445	Bronx	Bakery	1007	Morris Park Ave	10462

11. Update a record
Update the record whose value for nyc_restaurant_id is '30191841'. Change the name from 'Dj Reynolds Pub And Restaurant' to 'DJ Reynolds Pub and Restaurant'.
  UPDATE restaurants SET name='DJ REY REY' WHERE nyc_restaurant_id='30191841';

12. Delete by id
Delete the grade whose id is 10.
  DELETE FROM grades WHERE id='10';

13. A blocked delete
Try deleting the restaurant with id of 22. What error do you get?
  ERROR:  update or delete on table "restaurants" violates foreign key constraint "grades_restaurant_id_fkey" on table "grades"
  DETAIL:  Key (id)=(10) is still referenced from table "grades".
  practice=# SELECT * FROM restaurants WHERE id='10

Paste the error text for the answer. We'll learn about foreign key constraints in the next reading, but take two seconds and come up with your own theory about what this message means.

14. Create a table
Create a new table called inspectors with the following properties:

first_name: String of inspector's first name, required
last_name: String of inspector's last name, required
borough: The borough the inspector works in, not required, one of Bronx, Brooklyn, Manhattan, Queens, Staten Island.
inspectors should also have a system generated primary key property, id.

Note that the borough property requires you to use an enumerated type, which is a list of set values you can use for a property. You can use an existing enumerated type that will already be in the table: borough_options.

CREATE TYPE borough_type AS ENUM('Bronx', 'Brooklyn', 'Manhattan', 'Queens', 'Staten Island');

CREATE TABLE inspectors (
id INTEGER PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
first_name TEXT NOT NULL,
last_name TEXT NOT NULL,
borough borough_type);

15. Update a table
Add a notes field to the grades table. notes are not required, and are text.
  ALTER TABLE grades ADD COLUMN notes TEXT;

16. Drop a table
Drop the inspectors table from the database.
  DROP TABLE inspectors;