Tony 
Given the CITY and COUNTRY tables, query the sum of the populations of all cities where the CONTINENT is ‘Asia’.
Note: CITY.CountryCode and COUNTRY.Code are matching key columns.
Input Format
The CITY and COUNTRY tables are described as follows:
CITY
| Filed | Type |
|---|---|
| ID | NUMBER |
| NAME | VARCHAR2(17) |
| COUNTRYCODE | VARCHAR2(3) |
| DISTRICT | VARCHAR2(20) |
| POPULATION | NUMBER |
COUNTRY
| Filed | Type |
|---|---|
| CODE | VARCHAR2(3) |
| NAME | VARCHAR2(44) |
| CONTINENT | VARCHAR2(13) |
| REGION | VARCHAR2(25) |
| SURFACEAREA | NUMBER |
| INDEPYEAR | VARCHAR2(5) |
| POPULATION | NUMBER |
| LIFEEXPECTANCE | VARCHAR2(4) |
| GNP | NUMBER |
| GNPOLD | VARCHAR2(9) |
| LOCALNAME | VARCHAR2(44) |
| GOVERNMENTFORM | VARCHAR2(44) |
| HEADOFSTATE | VARCHAR2(32) |
| CAPITAL | VARCHAR2(4) |
| CODE2 | VARCHAR2(2) |
ANALYSIS
- JOIN two tables on CITY.CountryCode = COUNTRY.Code
- add the limitation where Country.continent = ‘Asia’
- Using SUM keyword to compute the total of city population.
ANS
SELECT SUM(CITY.POPULATION) FROM CITY JOIN COUNTRY ON CITY.CountryCode = COUNTRY.Code WHERE COUNTRY.CONTINENT=’Asia’
Expected Output
27028484
