<p>[QueryID:18]Give all pizzas that originate from the same country as the 'siciliano' pizza. The following steps may be helpful in formulating the query for the problem: Two ways to solve this problem:</p><p>Option 1: using a subquery</p><p>1. Mapping the data items required to the column names in the DB pizza name  pizza</p><p>2. Interpret the row selection condition  Pizza that originates from the same country as the ‘siciliano’ pizza  country = the country of the siciliano pizza and pizza <> siciliano</p><p>Note: “The country of origin of the ‘siciliano’ pizza” can be obtained by a subquery, which produces the country of origin of the ‘siciliano’ pizza. In order to form a logical expression using the subquery, use “=” to link the subquery as country = (subquery)</p><p> i. Mapping the data items required to the column names in the DB country of origin  country</p><p> ii. Interpret the row selection condition  Siciliano pizza  pizza = siciliano</p><p> iii. Identify the table(s) needed, which contains all the data items used in 1) and 2) menu table</p><p> iv. Group result or individual result No aggregate function is used  individual result, Group By is not needed. </p><p> v. Using the template: SELECT <list of columns or expressions > FROM <list of tables or join operations> WHERE <row selection condition ></p><p>3. Identify the table(s) needed, which contains all the data items used in 1) and 2) menu table 4. Group result or individual result No aggregate function is used  individual result, Group By is not needed. </p><p>5. Using the template: SELECT <list of columns or expressions > FROM <list of tables or join operations> WHERE <row selection condition including subquery></p><p>©H.Y Lu 2008 Option 2: -- using join</p><p>Consider two copies of the menu table, the first copy (m1) is for the selection pool of pizzas and the second one (m2) is for the siciliano pizza m2.pizza = siciliano</p><p>1. Mapping the data items required to the column names in the DB pizza name  pizza</p><p>2. Interpret the row selection condition  Pizza that originates from the same country as the ‘siciliano’ pizza  joining the two copies of the menu table based on the equality of country, and set row selection condition as m1.pizza <> siciliano and m2.pizza = siciliano</p><p>3. Identify the table(s) needed, which contains all the data items used in 1) and 2) menu m1 table and menu m2 table</p><p>4. How to join these two copies of menu table</p><p>Joining condition— m1.country = m2.country</p><p>Joining styles – in FROM, menu m1 join menu m2 on m1.country = m2.country or -- in FROM, menu m1, menu m2 and in WHERE, m1.country = m2.country </p><p>5. Group result or individual result No aggregate function is used  individual result, Group By is not needed. </p><p>6. Using the template: SELECT <list of columns or expressions > FROM <list of tables or join operations> WHERE <row selection condition ></p><p>©H.Y Lu 2008</p>