The tables we have

SHOW TABLES
Tables_in_test
0 nobel
1 world

GROUP BY is used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns.

-- format
SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
ORDER BY column_name(s);

Number of countries in each continent

SELECT continent, 
       COUNT(name) 
FROM   world 
GROUP  BY continent
continent COUNT(name)
0 Asia 47
1 Europe 42
2 Africa 53
3 Caribbean 11
4 South America 13
5 Eurasia 2
6 Oceania 14
7 North America 11

List each continent and the name of the country that comes first alphabetically.

Using GROUP BY and MIN

SELECT continent, 
       MIN(name) 
FROM   world 
GROUP  BY continent 
ORDER  BY continent;
continent MIN(name)
0 Africa Algeria
1 Asia Afghanistan
2 Caribbean Antigua and Barbuda
3 Eurasia Armenia
4 Europe Albania
5 North America Belize
6 Oceania Australia
7 South America Argentina

Top ten nobel prize winner countries

SELECT birth_country, 
       COUNT(birth_country) AS prize_count 
FROM   nobel 
WHERE  birth_country IS NOT NULL 
GROUP  BY birth_country 
ORDER  BY prize_count DESC 
LIMIT  10
birth_country nobel_count
0 United States of America 276
1 United Kingdom 88
2 Germany 70
3 France 53
4 Sweden 30
5 Japan 29
6 Russia 20
7 Netherlands 19
8 Italy 18
9 Canada 18

Number of nobel laureates born in particular month

SELECT Month(birth_date) AS 'month', 
       COUNT(*) 
FROM   nobel 
GROUP  BY month 
ORDER  BY month
Month COUNT(*)
0 NaN 29
1 0.0 1
2 1.0 72
3 2.0 65
4 3.0 77
5 4.0 72
6 5.0 80
7 6.0 87
8 7.0 75
9 8.0 84
10 9.0 84
11 10.0 89
12 11.0 72
13 12.0 82

Looks like the data has wrong incorrect birth date information for 30 laureates. Lets check.

SELECT year, full_name, birth_date
FROM nobel
WHERE Month(birth_date) IS NULL
      OR Month(birth_date) = 0.0
year full_name birth_date
0 1904 Institut de droit international (Institute of ... None
1 1910 Bureau international permanent de la Paix (Per... None
2 1917 Comité international de la Croix Rouge (Intern... None
3 1938 Office international Nansen pour les Réfugiés ... None
4 1944 Comité international de la Croix Rouge (Intern... None
5 1947 Friends Service Council (The Quakers) None
6 1947 American Friends Service Committee (The Quakers) None
7 1954 Office of the United Nations High Commissioner... None
8 1960 Albert John Lutuli 1898-00-00
9 1963 Comité international de la Croix Rouge (Intern... None
10 1963 Ligue des Sociétés de la Croix-Rouge (League o... None
11 1965 United Nations Children's Fund (UNICEF) None
12 1969 International Labour Organization (I.L.O.) None
13 1977 Amnesty International None
14 1981 Office of the United Nations High Commissioner... None
15 1985 International Physicians for the Prevention of... None
16 1988 United Nations Peacekeeping Forces None
17 1995 Pugwash Conferences on Science and World Affairs None
18 1997 International Campaign to Ban Landmines (ICBL) None
19 1999 Médecins Sans Frontières None
20 2001 United Nations (U.N.) None
21 2005 International Atomic Energy Agency (IAEA) None
22 2006 Grameen Bank None
23 2007 Intergovernmental Panel on Climate Change (IPCC) None
24 2009 Venkatraman Ramakrishnan None
25 2011 Saul Perlmutter None
26 2011 Saul Perlmutter None
27 2012 European Union (EU) None
28 2013 Organisation for the Prohibition of Chemical W... None
29 2015 National Dialogue Quartet None

As per wikipedia, Albert John Lutuli does not have exact birth date. And the rest of the records with NULL entries are of organisations. So our Group by query has given correct output

References