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 Count ( * ) FROM countrylanguage AS T1 WHERE T1.Language = "English" INTERSECT SELECT T2.Continent FROM country AS T2 JOIN countrylanguage AS T1 ON T2.Code = T1.CountryCode WHERE T1.Language = "Dutch"
Feedback: Exchange countrylanguage table with country table in step 1 and continent with country table .

SOLUTION: SELECT COUNT(*) FROM (SELECT T1.Name FROM country AS T1 JOIN countrylanguage AS T2 ON T1.Code  =  T2.CountryCode WHERE T2.Language  =  "English" INTERSECT SELECT T1.Name FROM country AS T1 JOIN countrylanguage AS T2 ON T1.Code  =  T2.CountryCode WHERE T2.Language  =  "Dutch")

PROBLEM: SQL: SELECT T2.District_name FROM store AS T1 JOIN district AS T2 JOIN store_district AS T3 ON T1.Store_ID = T3.Store_ID AND T3.District_ID = T2.District_ID WHERE T1.Store_Name = "City Mall" INTERSECT SELECT T2.District_name FROM store AS T1 JOIN district AS T2 JOIN store_district AS T3 ON T1.Store_ID = T3.Store_ID AND T3.District_ID = T2.District_ID WHERE T1.Store_Name = "Village Store"
Feedback: Change store name with type in both step 2 and step 3.

SOLUTION: SELECT t3.District_name FROM store AS t1 JOIN store_district AS t2 ON t1.store_id  =  t2.store_id JOIN district AS t3 ON t2.district_id  =  t3.district_id WHERE t1.Type  =  "City Mall" INTERSECT SELECT t3.District_name FROM store AS t1 JOIN store_district AS t2 ON t1.store_id  =  t2.store_id JOIN district AS t3 ON t2.district_id  =  t3.district_id WHERE t1.Type  =  "Village Store"

PROBLEM: SQL: SELECT acc_type , Avg ( no_of_loans ) FROM customer WHERE credit_score < 50 GROUP BY acc_type
Feedback: Ensure to find average account balance instead of number of loans .

SOLUTION:
SELECT avg(acc_bal) ,  acc_type FROM customer WHERE credit_score  <  50 GROUP BY acc_type