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. 

SQL: SELECT amenity_name FROM Dorm_amenity GROUP BY amenity_name ORDER BY Count ( * ) Desc LIMIT 1
Feedback: step 1 should have amenity id instead of amenity name and has amenity instead of dorm amenity
SELECT T1.amenity_name FROM dorm_amenity AS T1 JOIN has_amenity AS T2 ON T1.amenid  =  T2.amenid GROUP BY T2.amenid ORDER BY count(*) DESC LIMIT 1

SQL: SELECT name FROM buildings GROUP BY name HAVING Count ( * ) > 1
Feedback: Instep 1 , there should be company id of office locations instead of name in buildings table .
SELECT T2.name FROM Office_locations AS T1 JOIN buildings AS T2 ON T1.building_id  =  T2.id JOIN Companies AS T3 ON T1.company_id  =  T3.id GROUP BY T1.building_id HAVING COUNT(*)  >  1

SQL: SELECT T2.name FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name = T2.name WHERE T1.age > 40 INTERSECT SELECT T1.name FROM Person AS T1 WHERE T1.age < 30
Feedback: step 2: find person name . step 2 and 3: Need to find person's friend age instead of person .

SELECT T1.name FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name  =  T2.name WHERE T2.friend IN (SELECT name FROM Person WHERE age  >  40) INTERSECT SELECT T1.name FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name  =  T2.name WHERE T2.friend IN (SELECT name FROM Person WHERE age  <  30)