Problem 4.7. A GCS with the relation Country(Name, Continent, Population, Has- Coast) describes countries of the world. The attribute HasCoast indicates if the country has direct access to the sea. Three LCSs are connected to the global schema using the LAV approach as follows CREATE VIEW EuropeanCountry AS SELECT Name, Continent, Population, HasCoast FROM Country WHERE Continent"Europe CREATE VIEW BigCountry AS SELECT Name, Continent, Population, HasCoast FROM Country WHERE Population >-30000000 CREATE VIEW MidsizeOceanCountry AS SELECT Name, Continent, Population, HasCoast FROM Country WHERE HasCoast-true AND Population > 10000000 For each of the following queries, discuss the results with respect to their completeness, ie., verify if the (combination of the) local sources cover all relevant results. (a) 1. SELECT Name FROM Country 2. SELECT Name FROM Country WHERE Population > 40 3. SELECT Name FROM Country WHERE Population > 20 (b) For each of the following queries, discuss which of the three LCSs are necessary for the global query result . SELECT Name FROM Country 2. SELECT Name FROM Country WHERE Population30 AND Continent"Europe" 3. SELECT Name FROM Country WHERE Population 30 4. SELECT Name FROM Country WHERE Population 30 AND HasCoasttrue Problem 4.7. A GCS with the relation Country(Name, Continent, Population, Has- Coast) describes countries of the world. The attribute HasCoast indicates if the country has direct access to the sea. Three LCSs are connected to the global schema using the LAV approach as follows CREATE VIEW EuropeanCountry AS SELECT Name, Continent, Population, HasCoast FROM Country WHERE Continent"Europe CREATE VIEW BigCountry AS SELECT Name, Continent, Population, HasCoast FROM Country WHERE Population >-30000000 CREATE VIEW MidsizeOceanCountry AS SELECT Name, Continent, Population, HasCoast FROM Country WHERE HasCoast-true AND Population > 10000000 For each of the following queries, discuss the results with respect to their completeness, ie., verify if the (combination of the) local sources cover all relevant results. (a) 1. SELECT Name FROM Country 2. SELECT Name FROM Country WHERE Population > 40 3. SELECT Name FROM Country WHERE Population > 20 (b) For each of the following queries, discuss which of the three LCSs are necessary for the global query result . SELECT Name FROM Country 2. SELECT Name FROM Country WHERE Population30 AND Continent"Europe" 3. SELECT Name FROM Country WHERE Population 30 4. SELECT Name FROM Country WHERE Population 30 AND HasCoasttrue