Add missing ERD/SQL tabs and fix some requests
This commit is contained in:
Laurence Isla
committed by
Steve Chavez
Steve Chavez
parent
637165ba5b
commit
3f112553b0
@@ -24,7 +24,56 @@ Relationships
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For example, consider a database of films and their awards:
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.. image:: ../../_static/film.png
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.. _erd_film:
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.. tabs::
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.. group-tab:: ERD
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.. image:: ../../_static/film.png
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.. code-tab:: postgresql SQL
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create table actors(
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id int primary key generated always as identity,
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first_name text,
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last_name text
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);
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create table directors(
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id int primary key generated always as identity,
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first_name text,
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last_name text
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);
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create table films(
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id int primary key generated always as identity,
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director_id int references directors(id),
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title text,
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year int,
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rating numeric(3,1),
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language text
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);
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create table roles(
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film_id int references films(id),
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actor_id int references actors(id),
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character text,
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primary key(film_id, actor_id)
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);
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create table competitions(
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id int primary key generated always as identity,
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name text,
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year int
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);
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create table nominations(
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competition_id int references competitions(id),
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film_id int references films(id),
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rank int,
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primary key (competition_id, film_id)
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);
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.. _many-to-one:
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@@ -136,24 +185,7 @@ Many-to-many relationships
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The join table determines many-to-many relationships. It must contain foreign keys to other two tables and they must be part of its composite key.
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For the many-to-many relationship between ``films`` and ``actors``, the join table ``roles`` is:
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.. code-block:: postgresql
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create table roles(
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film_id int references films(id)
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, actor_id int references actors(id)
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, primary key(film_id, actor_id)
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);
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-- the join table can also be detected if the composite key has additional columns
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create table roles(
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id int generated always as identity,
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, film_id int references films(id)
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, actor_id int references actors(id)
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, primary key(id, film_id, actor_id)
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);
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Thus, it can detect the join table ``roles`` between ``films`` and ``actors``:
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.. tabs::
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@@ -177,6 +209,18 @@ For the many-to-many relationship between ``films`` and ``actors``, the join tab
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".."
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]
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The join table can also be detected if the composite key has additional columns:
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.. code-block:: postgresql
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create table roles(
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id int generated always as identity,
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, film_id int references films(id)
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, actor_id int references actors(id)
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, character text,
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, primary key(id, film_id, actor_id)
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);
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.. _one-to-one:
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One-to-one relationships
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@@ -184,38 +228,27 @@ One-to-one relationships
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One-to-one relationships are detected in two ways.
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- When the foreign key is a primary key as specified in the :ref:`DB structure example <erd_film>`.
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- When the foreign key has a unique constraint.
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.. code-block:: postgresql
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.. code-block:: postgresql
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CREATE TABLE technical_specs(
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film_id INT REFERENCES films UNIQUE,
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runtime TIME,
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camera TEXT,
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sound TEXT
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);
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- When the foreign key is a primary key.
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.. code-block:: postgresql
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-- references Films using the primary key as a foreign key
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CREATE TABLE technical_specs(
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film_id INT PRIMARY KEY REFERENCES films,
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runtime TIME,
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camera TEXT,
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sound TEXT
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);
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CREATE TABLE technical_specs(
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film_id INT REFERENCES films UNIQUE,
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runtime TIME,
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camera TEXT,
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sound TEXT
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);
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.. tabs::
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.. code-tab:: http
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GET /films?select=title,technical_specs(runtime) HTTP/1.1
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GET /films?select=title,technical_specs(camera) HTTP/1.1
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.. code-tab:: bash Curl
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curl "http://localhost:3000/films?select=title,technical_specs(runtime)"
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curl "http://localhost:3000/films?select=title,technical_specs(camera)"
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.. code-block:: json
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@@ -236,20 +269,26 @@ You can manually define relationships between using functions. This is useful fo
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Assuming there's a foreign table ``premieres`` that we want to relate to ``films``.
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.. code-block:: postgres
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.. tabs::
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create foreign table premieres (
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id integer,
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location text,
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"date" date,
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film_id integer
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) server import_csv options ( filename '/tmp/directors.csv', format 'csv');
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.. group-tab:: ERD
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create function film(premieres) returns setof films rows 1 as $$
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select * from films where id = $1.film_id
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$$ stable language sql;
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.. image:: ../../_static/premieres.png
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The above function defines a relationship between ``premieres`` (the parameter) and ``films`` (the return type). Since there's a ``rows 1``, this defines a many-to-one relationship.
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.. code-tab:: postgresql SQL
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create foreign table premieres (
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id integer,
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location text,
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"date" date,
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film_id integer
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) server import_csv options ( filename '/tmp/directors.csv', format 'csv');
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create function film(premieres) returns setof films rows 1 as $$
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select * from films where id = $1.film_id
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$$ stable language sql;
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The above function (see the **SQL** tab) defines a relationship between ``premieres`` (the parameter) and ``films`` (the return type). Since there's a ``rows 1``, this defines a many-to-one relationship.
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The name of the function ``film`` is arbitrary and can be used to do the embedding:
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.. tabs::
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@@ -698,24 +737,30 @@ Foreign Key joins can also be done between `partitioned tables <https://www.post
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For example, let's create the ``box_office`` partitioned table that has the gross daily revenue of a film:
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.. code-block:: postgres
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.. tabs::
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CREATE TABLE box_office (
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bo_date DATE NOT NULL,
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film_id INT REFERENCES test.films NOT NULL,
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gross_revenue DECIMAL(12,2) NOT NULL,
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PRIMARY KEY (bo_date, film_id)
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) PARTITION BY RANGE (bo_date);
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.. group-tab:: ERD
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-- Let's also create partitions for each month of 2021
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.. image:: ../../_static/boxoffice.png
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CREATE TABLE box_office_2021_01 PARTITION OF test.box_office
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FOR VALUES FROM ('2021-01-01') TO ('2021-01-31');
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.. code-tab:: postgresql SQL
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CREATE TABLE box_office_2021_02 PARTITION OF test.box_office
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FOR VALUES FROM ('2021-02-01') TO ('2021-02-28');
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CREATE TABLE box_office (
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bo_date DATE NOT NULL,
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film_id INT REFERENCES films NOT NULL,
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gross_revenue DECIMAL(12,2) NOT NULL,
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PRIMARY KEY (bo_date, film_id)
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) PARTITION BY RANGE (bo_date);
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-- and so until december 2021
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-- Let's also create partitions for each month of 2021
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CREATE TABLE box_office_2021_01 PARTITION OF box_office
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FOR VALUES FROM ('2021-01-01') TO ('2021-01-31');
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CREATE TABLE box_office_2021_02 PARTITION OF box_office
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FOR VALUES FROM ('2021-02-01') TO ('2021-02-28');
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-- and so until december 2021
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Since it contains the ``films_id`` foreign key, it is possible to join ``box_office`` and ``films``:
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