In this task you are expected to provide an SQL statement from an english description of what that SQL statement does. The description may include multiple steps but you should only ouput one SQL statement that accomplishes every step. An SQL query works by selecting data from a table where certain conditions apply. A table contains columns where every row in that table must have a value for each column. Every table has a primary key that uniquely identifies each row, usually an id. To choose which columns are returned you specify that after the "SELECT" statement. Next, you use a "FROM" statement to specify what tables you want to select the data from. When you specify a table you can rename it with the "AS" statement. You can reference that table by whatever name follows the "AS" statement. If you want to select data from multiple tables you need to use the "JOIN" statement. This will join the tables together by pairing a row in one table with every row in the other table (Cartesian Product). To limit the number of rows returned you should use the "ON" statement. This will only return rows where the condition specified after the statement is true, this is usually an equals operator with primary keys. You can also use the "WHERE" statement to specify that only rows with column values statisfying a certain condition, should be returned. The "GROUP BY" statement will group rows together that have equal column values for whatever columns follows the statement. The "HAVING" statement will return groups that statisfy whatever condition follows the statement. Any column(s) being returned from grouped rows must either be an aggregate function, (AVG, MAX, COUNT, SUM, ...) of a column, or the column(s) that the data was grouped by. To sort the returned data you can use the "ORDER BY" command which will order the data by whatever aggregate function or column follows the statement. The "DESC" statement will sort in descending order and the "ASC" statement will sort in ascending order. Finally, you can use the "LIMIT" statement to return a certain number of rows. When "*" is used in an SQL statement every column is returned. For example, SELECT * FROM table WHERE attribute = 1, will select every column from rows with the attribute column equal to 1.

Step 1: find the number of rows of each value of Product_Name in Products table.
Step 2: find Product_Name in Products table whose corresponding value in step 1 is greater than or equals 2
SELECT Product_Name FROM Products GROUP BY Product_Name HAVING Count ( * ) > = 2

Step 1: For each row in medicine_enzyme_interaction table, find corresponding rows in medicine table and in enzyme table.
Step 2: find Trade_Name, medicine's name of the results of step 1 whose Porphyria equals inhibitor.
Step 3: find Trade_Name, medicine's name of the results of step 1 whose Porphyria equals activitor.
Step 4: show the rows that are in both the results of step 2 and the results of step 3
SELECT T1.Trade_Name , T1.name FROM medicine AS T1 JOIN enzyme AS T2 JOIN medicine_enzyme_interaction AS T3 ON T1.id = T3.medicine_id AND T3.enzyme_id = T2.id WHERE T2.Porphyria = "inhibitor" INTERSECT SELECT T1.Trade_Name , T1.name FROM medicine AS T1 JOIN enzyme AS T2 JOIN medicine_enzyme_interaction AS T3 ON T1.id = T3.medicine_id AND T3.enzyme_id = T2.id WHERE T2.Porphyria = "activitor"

Step 1: For each row in Campuses table, find corresponding rows in csu_fees table and in discipline_enrollments table.
Step 2: find the average CampusFee in the results of step 1 whose csu_fees's Year equals 2005 and Discipline equals 4

SELECT Avg ( T2.CampusFee ) FROM Campuses AS T1 JOIN csu_fees AS T2 ON T2.Campus = T1.Id JOIN discipline_enrollments AS T3 ON T1.Id = T3.Campus WHERE T2.Year = 2005 AND T3.Discipline = 4