Prima Formă Normală

Crearea bazelor de date PostgreSQL

Darryl Reeves

Industry Assistant Professor, New York University

Exemplu: gestionarea înregistrărilor studenților

CREATE TABLE student (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    courses VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

Erori de actualizare
Erori de inserție
Erori de ștergere

Exemplu: date duplicate după actualizare

id	name	courses	home_room
122	Susan Roth	Algebra I, Physics, Spanish II	101
413	Robert Cruz	History, Geometry, Biology	204
613	Thomas Wright	English III, Chemistry, Algebra II	102

Exemplu: date duplicate după actualizare

id	name	courses	home_room
122	Susan Roth	Algebra I, Chemistry, Spanish II	101
413	Robert Cruz	History, Geometry, Biology	204
613	Thomas Wright	English III, Chemistry, Algebra II	102

Exemplu: date duplicate după actualizare

id	name	courses	home_room
122	Susan Roth	Algebra I, Chemistry, Spanish II, Chemistry	101
413	Robert Cruz	History, Geometry, Biology	204
613	Thomas Wright	English III, Chemistry, Algebra II	102

Exemplu: inserții cu restricții de coloană

CREATE TABLE student (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    courses VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

id	name	courses	home_room
122	Susan Roth	Algebra I, Physics, Spanish II	101
413	Robert Cruz	History, Geometry, Biology	204
613	Thomas Wright	English III, Chemistry, Algebra II	102

Exemplu: inserții cu restricții de coloană

CREATE TABLE student (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    courses VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

id	name	courses	home_room
122	Susan Roth	Algebra I, Physics, Spanish II	101
413	Robert Cruz	History, Geometry, Biology, French Literature	204
613	Thomas Wright	English III, Chemistry, Algebra II	102

Exemplu: integritatea datelor afectată de ștergerea înregistrărilor

id	name	courses	home_room
122	Susan Roth	Algebra I, Physics, Spanish II	101
413	Robert Cruz	History, Geometry, Biology	204
613	Thomas Wright	English III, Chemistry, Algebra II	102

Exemplu: integritatea datelor afectată de ștergerea înregistrărilor

id	name	courses	home_room
122	Susan Roth	Algebra I, Physics, Spanish II	101
413	Robert Cruz	History, Geometry, Biology	204
613	Thomas Wright	???	102

Satisfacerea Primei Forme Normale (1NF)

Cerință 1NF:
- Valorile din tabel trebuie să fie atomice

Exemplu: tabelul student satisface 1NF

CREATE TABLE student (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    courses VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

Exemplu: tabelul student satisface 1NF

CREATE TABLE student (
    id INTEGER,
    name VARCHAR(50) NOT NULL,
    courses VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

Exemplu: tabelul student satisface 1NF

CREATE TABLE student (
    id INTEGER,
    name VARCHAR(50) NOT NULL,
    course VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

Exemplu: tabelul student satisface 1NF

id	name	course	home_room
122	Susan Roth	Algebra I	101
122	Susan Roth	Physics	101
122	Susan Roth	Spanish II	101
413	Robert Cruz	History	204
413	Robert Cruz	Geometry	204
413	Robert Cruz	Biology	204

Exemplu: tabelul student satisface 1NF

CREATE TABLE student (
    id INTEGER,
    name VARCHAR(50) NOT NULL,
    course VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

Exemplu: tabelul student satisface 1NF

CREATE TABLE student (
    student_id INTEGER,
    first_name VARCHAR(50) NOT NULL,
    last_name VARCHAR(50) NOT NULL,
    course VARCHAR(50) NOT NULL,
    home_room SMALLINT NOT NULL
);

Exemplu: tabelul student satisface 1NF

id	first_name	last_name	course	home_room
122	Susan	Roth	Algebra I	101
122	Susan	Roth	Physics	101
122	Susan	Roth	Spanish II	101
413	Robert	Cruz	History	204
413	Robert	Cruz	Geometry	204
413	Robert	Cruz	Biology	204

Să exersăm!

Crearea bazelor de date PostgreSQL