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 title , credits , dept_name FROM course GROUP BY dept_name HAVING Count ( * ) > 1
Feedback: Find number of rows of each value of course id in prerequisite table in step 1.

SOLUTION: SELECT T1.title ,  T1.credits , T1.dept_name FROM course AS T1 JOIN prereq AS T2 ON T1.course_id  =  T2.course_id GROUP BY T2.course_id HAVING count(*)  >  1

PROBLEM: SQL: SELECT T1.state FROM College AS T1 JOIN Tryout AS T2 ON T1.cName = T2.cName WHERE T2.pPos = "goalie" INTERSECT SELECT T2.cName FROM Tryout AS T2 WHERE T2.pPos = "mid"
Feedback: In step 3 , need to find "state" instead of "Tryout's college name of tryout table"

SOLUTION: SELECT T1.state FROM college AS T1 JOIN tryout AS T2 ON T1.cName  =  T2.cName WHERE T2.pPos  =  'goalie' INTERSECT SELECT T1.state FROM college AS T1 JOIN tryout AS T2 ON T1.cName  =  T2.cName WHERE T2.pPos  =  'mid'

PROBLEM: SQL: SELECT Avg ( screen_mode ) FROM phone WHERE Company_name = "Nokia Corporation"
Feedback: Replace screen mode in phone table with rom mib in chip model table .

SOLUTION:
SELECT avg(T1.ROM_MiB) FROM chip_model AS T1 JOIN phone AS T2 ON T1.Model_name  =  T2.chip_model WHERE T2.Company_name = "Nokia Corporation"