Aktualisieren der Datenbank nach geänderter Struktur

Einführung in relationale Datenbanken in SQL

Timo Grossenbacher

Data Journalist

Aktuelles Datenbankmodell

Nur unterschiedliche Daten (DISTINCT) in neuen Tabellen speichern

SELECT COUNT(*)
FROM university_professors;

 count
 -----
 1377

SELECT COUNT(DISTINCT organization) 
FROM university_professors;

 count
 -----
 1287

Unterschiedliche Daten in neue Tabellen einfügen (INSERT DISTINCT INTO)

INSERT INTO organizations 
SELECT DISTINCT organization, 
    organization_sector
FROM university_professors;

Output: INSERT 0 1287

INSERT INTO organizations 
SELECT organization, 
    organization_sector
FROM university_professors;

Output: INSERT 0 1377

Die Anweisung „INSERT INTO“

INSERT INTO table_name (column_a, column_b)
VALUES ("value_a", "value_b");

Spalte in der Tabelle „affiliations“ umbenennen (RENAME COLUMN)

CREATE TABLE affiliations (
 firstname text,
 lastname text,
 university_shortname text,
 function text,
 organisation text
);

ALTER TABLE table_name
RENAME COLUMN old_name TO new_name;

Spalte in der Tabelle „affiliations“ löschen (DROP COLUMN)

CREATE TABLE affiliations (
 firstname text,
 lastname text,
 university_shortname text,
 function text,
 organization text
);

ALTER TABLE table_name
DROP COLUMN column_name;

SELECT DISTINCT firstname, lastname, 
    university_shortname 
FROM university_professors
ORDER BY lastname;

-[ RECORD 1 ]--------+-------------
firstname            | Karl
lastname             | Aberer
university_shortname | EPF
-[ RECORD 2 ]--------+-------------
firstname            | Reza Shokrollah
lastname             | Abhari
university_shortname | ETH
-[ RECORD 3 ]--------+-------------
firstname            | Georges
lastname             | Abou Jaoudé
university_shortname | EPF
(truncated)

(551 records)

SELECT DISTINCT firstname, lastname 
FROM university_professors
ORDER BY lastname;

-[ RECORD 1 ]----------------------
firstname | Karl
lastname  | Aberer
-[ RECORD 2 ]----------------------
firstname | Reza Shokrollah
lastname  | Abhari
-[ RECORD 3 ]----------------------
firstname | Georges
lastname  | Abou Jaoudé
(truncated)

(551 records)

Ein Professor wird eindeutig mit Vorname und Nachname identifiziert

Lass uns loslegen!

Einführung in relationale Datenbanken in SQL