TASK DEFINITION: In this task you are expected to fix an SQL query based on feedback. You will be given an SQL statement and an English description with what is wrong about that SQL statement. You must correct the SQL statement based off of the feedback. 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: SQL: SELECT T2.product_id , T1.customer_id FROM Customer_Orders AS T1 JOIN Order_Items AS T2 ON T1.order_id = T2.order_id WHERE T1.order_status_code = "Paid" OR T1.order_status_code = "Cancelled"
Feedback: Ensure to use order shipping charges instead of product id .

SOLUTION: SELECT order_shipping_charges ,  customer_id FROM customer_orders WHERE order_status_code  =  'Cancelled' OR order_status_code  =  'Paid'

PROBLEM: SQL: SELECT T2.student_id , T1.city FROM Addresses AS T1 JOIN Student_Addresses AS T2 ON T1.address_id = T2.address_id GROUP BY T2.student_id ORDER BY Avg ( T2.monthly_rental ) Desc LIMIT 1
Feedback: Just find average monthly rental , no need to find for each value of student id .

SOLUTION: SELECT T2.address_id ,  T1.city FROM Addresses AS T1 JOIN Student_Addresses AS T2 ON T1.address_id  =  T2.address_id GROUP BY T2.address_id ORDER BY AVG(monthly_rental) DESC LIMIT 1

PROBLEM: SQL: SELECT candidate_id FROM Candidate_Assessments GROUP BY candidate_id ORDER BY Count ( * ) Desc LIMIT 1
Feedback: In step 1 , need to find assessment date for each candidate id .

SOLUTION:
SELECT candidate_id FROM candidate_assessments ORDER BY assessment_date DESC LIMIT 1