Scottish Parliament/zh
蘇格蘭議會
這些數據包括蘇格蘭議會1999年的全部成員。大部份成員都屬於政黨。有些政黨的領導人在議會中。有兩個表格:
Name名字 | Party政黨 | Constituency選區 |
---|---|---|
Adam MSP, Brian | SNP | North East Scotland |
Aitken MSP, Bill | Con | Glasgow |
Alexander MSP, Ms Wendy | Lab | Paisley North |
...記錄總數: 129 |
Code代碼 | Name政黨名 | Leader領導人 |
---|---|---|
Con | Conservative | McLetchie MSP, David |
Green | Green | |
Lab | Labour | Dewar MSP, Rt Hon Donald |
... 記錄總數: 9 |
處理NULL
一個成員被工黨逐出黨,現沒屬任何黨。找出他。
You might think that the phrase dept=NULL would work here. It doesn't. This is because NULL "propogates". Any normal expression that includes NULL is itself NULL, thus the value of the expressions 2+NULL and party || NULL and NULL=NULL for example are all NULL.
The NULL
value does not cause a type error, however it does infect everything it touches with NULL
-ness. We call this element the bottom
value for the algebra - but we don't snigger because we are grown-ups. Bottom Type.
SELECT name FROM msp WHERE party IS NULL
列出每個黨及其領導人。
SELECT name, leader FROM party
列出每個黨及其領導人,這些黨其實是沒有領導人的。
SELECT name, leader FROM party
WHERE leader IS NOT NULL
列出政黨名單,當中最少有一名黨員在議會內。
SELECT DISTINCT party.name FROM msp, party
WHERE party=code
列出議會成員的名單,如有所屬政黨,一同列出。確保 Canavan MSP, Dennis
是在名單中。
按msp.name順序排列。
SELECT msp.name, party.name
FROM msp LEFT JOIN party ON party=code
ORDER BY msp.name
列出議會中每一政黨的黨員人數。
SELECT party.name, COUNT(msp.name)
FROM msp, party
WHERE msp.party=party.code
GROUP BY party.name
列出每一政黨的議會中黨員人數,包括沒有黨員在議會中的政黨。
SELECT party.name, COUNT(msp.name)
FROM party
LEFT JOIN msp ON party.code=msp.party
GROUP BY party.name
Self joins are the topic for the next tutorial
Note
Sadly Donald Dewar died in 2000. An able and popular leader of the Labour Party in Scotland.