Update 3. Get Only What You Need, and Fast.md

Author: ortizfram

Introduction to MongoDB in Python/3. Get Only What You Need, and Fast.md

@@ -24,8 +24,10 @@ will fetch documents where the field 'name' ***starts with "Py".***
 
 > In this exercise, you will use regular expressions, projection, and list comprehension to collect the full names of laureates whose initials are "G.S.".
 
-- [x] 1. First, use regular expressions to fetch the documents for the laureates whose "firstname" starts with "G" and whose "surname" starts with "S".
-- [x] 2. Use projection and adjust the query to select only the "firstname" and "surname" fields.
+- [x] 1) First, use regular expressions to fetch the documents for the laureates whose "firstname" starts with "G" and whose "surname" starts with 
+         "S".
+- [x] 2) Use projection and adjust the query to select only the "firstname" and "surname" fields.
+- [x] 3) Iterate over the documents, and for each document, concatenate the first name and the surname fields together with a space in between to obtain full names.
 
 ```py
 # Find laureates whose first name starts with "G" and last name starts with "S"
@@ -36,3 +38,26 @@ docs = db.laureates.find(
 print(docs[0])
 ```
 ```py
+# Use projection to select only firstname and surname
+docs = db.laureates.find(
+    filter={"firstname": {"$regex": "^G"},
+            "surname": {"$regex": "^S"}},
+    projection=["firstname", "surname"])
+
+
+# Print the first document
+print(docs[0])
+```
+```py
+# Use projection to select only firstname and surname
+docs = db.laureates.find(
+       filter= {"firstname" : {"$regex" : "^G"},
+                "surname" : {"$regex" : "^S"}  },
+   projection= ["firstname", "surname"]  )
+
+# Iterate over docs and concatenate first name and surname
+full_names = [doc["firstname"] + " " + doc["surname"]  for doc in docs]
+
+# Print the full names
+print(full_names)
+```