'README.md' updaten

README.md

@@ -45,6 +45,19 @@ Use aliases for the tables. This should return 118 rows.
 
 Sort the final result set by vendor_name, invoice_date, invoice_number, and invoice_sequence.
 
+###Exercise 5
+
+Write a SELECT statement that returns three columns: 
+
+**vendor_id** (The vendor_id column from the Vendors table)  
+**vendor_name** (The vendor_name column from the Vendors table)  
+**contact_name** (A concatenation of the vendor_contact_first_name and vendor_contact_last_name columns with a space between)  
+
+Return one row for each vendor whose contact has the same last name as another vendor’s contact. This should return 2 rows. 
+
+*Hint: Use a self-join to check that the vendor_id columns aren’t equal but the vendor_contact_last_name columns are equal.*
+
+Sort the result set by vendor_contact_last_name.