Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Update intermediate_sql_class_notes.md #7

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Update intermediate_sql_class_notes.md #7

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 5 additions & 5 deletions intermediate_sql_class_notes.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -34,11 +34,11 @@ WHERE ORDER_DATE = (SELECT MAX(ORDER_DATE) FROM CUSTOMER_ORDER)
Sometimes it can be helpful to leverage subqueries that return a set of values, rather than one scalar value. For instance, to query customer orders for customers in TX, we can save ourselves a join and use a subquery to get CUSTOMER_ID's that belong to customers in TX. Then we can leverage that with a WHERE and specify an `IN` condition:

```sql
SELECT CUSTOMER_ORDER_ID,
SELECT ORDER_ID,
CUSTOMER_ID,
ORDER_DATE,
PRODUCT_ID,
QUANTITY
ORDER_QTY

FROM CUSTOMER_ORDER

Expand All @@ -54,13 +54,13 @@ WHERE CUSTOMER_ID IN (
Retrieving the average of quantity by each record's CUSTOMER_ID and PRODUCT_ID

```sql
SELECT CUSTOMER_ORDER_ID,
SELECT ORDER_ID,
CUSTOMER_ID,
ORDER_DATE,
PRODUCT_ID,
QUANTITY,
ORDERR_QTY,
(
SELECT AVG(QUANTITY)
SELECT AVG(ORDER_QTY)
FROM CUSTOMER_ORDER c2
WHERE c2.CUSTOMER_ID = c1.CUSTOMER_ID
AND c2.PRODUCT_ID = c1.PRODUCT_ID
Expand Down