Write the following SQL statements to query the NDX table in the dbclass schema/database. Your SQL statement should display only the columns identified unless otherwise specified.

1. Display the ChangeClose on the day Wednesday.

2. Display the average ChangeClose grouped by TMonth, TYear. Show the TYear, TMonth, and the average ChangeClose in that grouping.

Subqueries and Outer Joins

shipper

Column	Data Type	Description
shipper_id	int	primary key
shipper_name	varchar	name

shipment

Column	Data Type	Description
shipper_id	int	foreign key (exported from shipper table)
source	varchar
destination	varchar
completed	char

3. Write a SQL subquery which determines which records in the shipper table have no related records in the shipment table.

4. Write a SQL subquery which determines which records in the shipment table have no related records in the shipper table.

5. Write an outer join which joins the shipper table to the shipment table. This select statement should retrieve shipper table records whether or not they have corresponding records in the shipment table.

OPTIONAL EXTRA CREDIT

Use a correlated subquery between the shipper table and the shipment table to determine which shippers have not made any shipments. The correlated subquery must use and EXISTS clause.