Sortieren und Filtern

Einführung in SQL Server

John MacKintosh

Instructor

Schön der Reihe nach!

Tabellen bestehen aus Zeilen und Spalten
Abfragen geben Mengen oder Teilmengen zurück

Mengen haben keine bestimmte Reihenfolge
Wenn Reihenfolge wichtig ist: ORDER BY

SELECT TOP (10) prod_id, year_intro 
FROM products 
-- Order in ascending order
ORDER BY year_intro, product_id;


+------------+-------------+
| product_id | year_intro  |
|------------+-------------|
| 36         |  1981       |
| 37         |  1982       |
| 38         |  1983       |
| 39         |  1984       |
| 40         |  1984       |
| 41         |  1984       |
| 52         |  1985       |
| 43         |  1986       |
| 44         |  1987       |
| 54         |  1987       |
+------------+-------------+

SELECT TOP (10) product_id, year_intro 
FROM products 
-- Order year_intro in descending order
ORDER BY year_intro DESC, product_id;


+------------+-------------+
| product_id | year_intro  |
|------------+-------------|
| 158        |  2015       |
| 173        |  2015       |
| 170        |  2014       |
| 171        |  2014       |
| 172        |  2014       |
| 144        |  2013       |
| 146        |  2013       |
| 147        |  2013       |
| 148        |  2013       |
| 149        |  2013       |
+------------+-------------+

SELECT 
  TOP (10) appearances, 
  year_intro 
FROM products 
-- Order in different directions
ORDER BY 
  year_intro DESC, 
  appearances;


+-------------+------------+
| appearances | year_intro |
|-------------+------------|
| 35          | 2015       |
| 74          | 2015       |
| 29          | 2014       |
| 45          | 2014       |
| 48          | 2014       |
| 12          | 2013       |
| 13          | 2013       |
| 14          | 2013       |
| 22          | 2013       |
| 24          | 2013       |
+-------------+------------+

SELECT 
  TOP (10) appearances, 
  year_intro 
FROM products 
-- Both columns in descending order
ORDER BY 
  year_intro DESC, 
  appearances DESC;


+-------------+------------+
| appearances | year_intro |
|-------------+------------|
| 74          | 2015       |
| 35          | 2015       |
| 48          | 2014       |
| 45          | 2014       |
| 29          | 2014       |
| 837         | 2013       |
| 642         | 2013       |
| 561         | 2013       |
| 491         | 2013       |
| 198         | 2013       |
+-------------+------------+

SELECT city_id, name_alias
FROM invoice
-- Ordering text (Ascending order)
ORDER BY name_alias;


+-------------+----------------+
| city_id     | name_alias     |
|-------------+----------------|
|  48         | Amsterdam      |
|  59         | Bangalore      |
|  36         | Berlin         |
|  38         | Berlin         |
|  42         | Bordeaux       |
|  23         | Boston         |
|  13         | Brasília       |
|   8         | Brussels       |
|  45         | Budapest       |
|  56         | Buenos Aires   |
+-------------+----------------+

SELECT city_id, name_alias 
FROM invoice
-- Ordering text (Descending order)
ORDER BY name_alias DESC;


+-------------+----------------+
| city_id     | name_alias     |
|-------------+----------------|
|  33         | Yellowknife    |
|  32         | Winnipeg       |
|  49         | Warsaw         |
|   7         | Vienne         |
|  15         | Vancouver      |
|  27         | Tucson         |
|  29         | Toronto        |
|   2         | Stuttgart      |
|  51         | Stockholm      |
|  55         | Sydney         |
+-------------+----------------+

Was, wenn wir nur Zeilen zurückgeben wollen, die bestimmte Kriterien erfüllen?

SELECT customer_id, total
FROM invoice 
WHERE total > 15;

Die ersten 3 Personen mit einem Rechnungswert > 15

+-------------+------------+
| customer_id | total      |
|-------------+------------|
| 57          | 17.91      |
|  7          | 18.86      |
| 45          | 21.86      |
+-------------+------------+

-- Rows with points greater than 10
WHERE points > 10

-- Rows with points less than 10
WHERE points  < 10

-- Rows with points greater than or equal to 10
WHERE points >= 10

-- Rows with points less than or equal to 20
WHERE points  <= 20

-- Character data type
WHERE country = 'Spain'

-- Date data type 
WHERE event_date = '2012-01-02'

SELECT customer_id, total 
FROM invoice 
-- Testing for non-equality
WHERE total <> 10;

+------------+-------+
| customer_id | total |
|------------+-------|
| 2          | 1.98  |
| 4          | 3.96  |
| 8          | 5.94  |
| 14         | 8.91  |
| 23         | 13.86 |
| 37         | 0.99  |
+------------+-------+

BETWEEN

SELECT customer_id, total 
FROM invoice 
WHERE total BETWEEN 20 AND 30;

+------------+--------+
| customer_id | total  |
|------------+--------|
| 45         | 21.86  |
| 46         | 21.86  |
| 26         | 23.86  |
| 6          | 25.86  |
+------------+--------+

SELECT customer_id, total 
FROM invoice 
WHERE total NOT BETWEEN 20 AND 30;

+------------+--------+
| customerid | total  |
|------------+--------|
|  2         | 1.98   |
|  4         | 3.96   |
|  8         | 5.94   |
| 14         | 8.91   |
+------------+--------+

Was ist NULL?

NULL zeigt an, dass es keinen Wert für diesen Datensatz gibt.
NULL-Werte helfen, Lücken in unseren Daten zu erkennen.

SELECT 
  TOP (6) total, 
  billing_state 
FROM invoice 
WHERE billing_state IS NULL;

+-------+---------------+
| total | billing_state |
|-------+---------------|
| 1.98  | NULL          |
| 3.96  | NULL          |
| 5.94  | NULL          |
| 0.99  | NULL          |
| 1.98  | NULL          |
| 1.98  | NULL          |
+-------+---------------+

SELECT 
  TOP (6) total, 
  billing_state 
FROM invoice 
WHERE billing_state IS NOT NULL;

+--------+---------------+
| total  | billing_state |
|--------+---------------|
|  8.91  | AB            |
| 13.96  | MA            |
|  5.94  | Dublin        |
|  0.99  | CA            |
|  1.98  | WA            |
|  1.98  | CA            |
+-------+----------------+

Lass uns üben!

Einführung in SQL Server