TASK DEFINITION: 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.
PROBLEM: Step 1: find the number of rows of each value of owner_id in Owners table.
Step 2: find owner_id, first_name, last_name of Owners table with largest value in the results of step 1

SOLUTION: SELECT owner_id , first_name , last_name FROM Owners GROUP BY owner_id ORDER BY Count ( * ) Desc LIMIT 1

PROBLEM: Step 1: find the dorm_name of Dorm table.
Step 2: For each row in Has_amenity table, find corresponding rows in Dorm table and in Dorm_amenity table.
Step 3: find dorm_name of the results of step 2 whose amenity_name equals Study Room.
Step 4: show the rows that are in the results of step 1 but not in the results of step 3

SOLUTION: SELECT T1.dorm_name FROM Dorm AS T1 EXCEPT SELECT T1.dorm_name FROM Dorm AS T1 JOIN Dorm_amenity AS T2 JOIN Has_amenity AS T3 ON T1.dormid = T3.dormid AND T3.amenid = T2.amenid WHERE T2.amenity_name = "Study Room"

PROBLEM: Step 1: For each row in artist table, find the corresponding rows in song table.
Step 2: find artist's artist_name, artist's country of the results of step 1 whose rating greater than 900

SOLUTION:
SELECT T1.artist_name , T1.country FROM artist AS T1 JOIN song AS T2 ON T1.artist_name = T2.artist_name WHERE T2.rating > 900