Assignment two

02_activities/assignments/Cohort_8/assignment2.sql

@@ -11,14 +11,16 @@ SELECT
 product_name || ', ' || product_size|| ' (' || product_qty_type || ')'
 FROM product
 
+
 But wait! The product table has some bad data (a few NULL values). 
-Find the NULLs and then using COALESCE, replace the NULL with a 
-blank for the first problem, and 'unit' for the second problem. 
+Find the NULLs and then using COALESCE, replace the NULL with a blank for the first column with
+nulls, and 'unit' for the second column with nulls. 
 
-HINT: keep the syntax the same, but edited the correct components with the string. 
+**HINT**: keep the syntax the same, but edited the correct components with the string. 
 The `||` values concatenate the columns into strings. 
 Edit the appropriate columns -- you're making two edits -- and the NULL rows will be fixed. 
-All the other rows will remain the same.) */
+All the other rows will remain the same. */
+
 
 
 

02_activities/assignments/DC_Cohort/assignment2.sql

@@ -11,16 +11,21 @@ SELECT
 product_name || ', ' || product_size|| ' (' || product_qty_type || ')'
 FROM product
 
+
 But wait! The product table has some bad data (a few NULL values). 
-Find the NULLs and then using COALESCE, replace the NULL with a 
-blank for the first problem, and 'unit' for the second problem. 
+Find the NULLs and then using COALESCE, replace the NULL with a blank for the first column with
+nulls, and 'unit' for the second column with nulls. 
 
-HINT: keep the syntax the same, but edited the correct components with the string. 
+**HINT**: keep the syntax the same, but edited the correct components with the string. 
 The `||` values concatenate the columns into strings. 
 Edit the appropriate columns -- you're making two edits -- and the NULL rows will be fixed. 
-All the other rows will remain the same.) */
-
+All the other rows will remain the same. */
 
+SELECT 
+    product_name || ', ' || 
+    COALESCE(product_size || ' ', '') || 
+    '(' || COALESCE(product_qty_type, 'unit') || ')' AS product_description
+FROM product;
 
 --Windowed Functions
 /* 1. Write a query that selects from the customer_purchases table and numbers each customer’s  
@@ -32,18 +37,36 @@ each new market date for each customer, or select only the unique market dates p
 (without purchase details) and number those visits. 
 HINT: One of these approaches uses ROW_NUMBER() and one uses DENSE_RANK(). */
 
-
+SELECT 
+    customer_id,
+    market_date,
+    ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY market_date) AS visit_number
+FROM customer_purchases
+ORDER BY customer_id, market_date;
 
 /* 2. Reverse the numbering of the query from a part so each customer’s most recent visit is labeled 1, 
 then write another query that uses this one as a subquery (or temp table) and filters the results to 
 only the customer’s most recent visit. */
 
-
+WITH ranked_visits AS (
+    SELECT 
+        customer_id,
+        market_date,
+        ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY market_date DESC) AS visit_rank
+    FROM customer_purchases
+)
+SELECT customer_id, market_date
+FROM ranked_visits
+WHERE visit_rank = 1
+ORDER BY customer_id;
 
 /* 3. Using a COUNT() window function, include a value along with each row of the 
 customer_purchases table that indicates how many different times that customer has purchased that product_id. */
 
-
+SELECT *,
+       COUNT(*) OVER (PARTITION BY customer_id, product_id) AS times_purchased_this_product
+FROM customer_purchases
+ORDER BY customer_id, product_id, market_date;
 
 -- String manipulations
 /* 1. Some product names in the product table have descriptions like "Jar" or "Organic". 
@@ -57,11 +80,17 @@ Remove any trailing or leading whitespaces. Don't just use a case statement for
 
 Hint: you might need to use INSTR(product_name,'-') to find the hyphens. INSTR will help split the column. */
 
-
+SELECT 
+    product_name,
+    NULLIF(TRIM(SUBSTR(product_name, INSTR(product_name, '-') + 1)), '') AS description
+FROM product
+WHERE INSTR(product_name, '-') > 0;
 
 /* 2. Filter the query to show any product_size value that contain a number with REGEXP. */
 
-
+SELECT *
+FROM product
+WHERE product_size REGEXP '[0-9]';
 
 -- UNION
 /* 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.
@@ -73,7 +102,32 @@ HINT: There are a possibly a few ways to do this query, but if you're struggling
 3) Query the second temp table twice, once for the best day, once for the worst day, 
 with a UNION binding them. */
 
-
+WITH daily_sales AS (
+    SELECT 
+        market_date,
+        SUM(quantity * cost_to_customer_per_qty) AS total_sales
+    FROM customer_purchases
+    GROUP BY market_date
+),
+ranked AS (
+    SELECT 
+        market_date,
+        total_sales,
+        RANK() OVER (ORDER BY total_sales DESC) AS best_rank,
+        RANK() OVER (ORDER BY total_sales ASC)  AS worst_rank
+    FROM daily_sales
+)
+SELECT market_date, total_sales, 'Highest sales day' AS label
+FROM ranked 
+WHERE best_rank = 1
+
+UNION ALL
+
+SELECT market_date, total_sales, 'Lowest sales day' AS label
+FROM ranked 
+WHERE worst_rank = 1
+
+ORDER BY total_sales DESC;
 
 
 /* SECTION 3 */
@@ -89,27 +143,49 @@ Think a bit about the row counts: how many distinct vendors, product names are t
 How many customers are there (y). 
 Before your final group by you should have the product of those two queries (x*y).  */
 
-
+SELECT 
+    v.vendor_name,
+    p.product_name,
+    5 * COUNT(DISTINCT c.customer_id) * vi.quantity * vi.original_price AS potential_revenue
+FROM vendor_inventory vi
+JOIN vendor v     ON vi.vendor_id = v.vendor_id
+JOIN product p    ON vi.product_id = p.product_id
+CROSS JOIN customer c
+GROUP BY v.vendor_name, p.product_name
+ORDER BY potential_revenue DESC;
 
 -- INSERT
 /*1.  Create a new table "product_units". 
 This table will contain only products where the `product_qty_type = 'unit'`. 
 It should use all of the columns from the product table, as well as a new column for the `CURRENT_TIMESTAMP`.  
 Name the timestamp column `snapshot_timestamp`. */
 
-
+DROP TABLE IF EXISTS product_units;
+CREATE TABLE product_units AS
+SELECT *, CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM product
+WHERE product_qty_type = 'unit';
 
 /*2. Using `INSERT`, add a new row to the product_units table (with an updated timestamp). 
 This can be any product you desire (e.g. add another record for Apple Pie). */
 
-
+INSERT INTO product_units
+SELECT *, CURRENT_TIMESTAMP
+FROM product
+WHERE product_name = 'Apple Pie';
 
 -- DELETE
 /* 1. Delete the older record for the whatever product you added. 
 
 HINT: If you don't specify a WHERE clause, you are going to have a bad time.*/
 
-
+DELETE FROM product_units
+WHERE product_name = 'Apple Pie'
+  AND snapshot_timestamp = (
+    SELECT MIN(snapshot_timestamp)
+    FROM product_units
+    WHERE product_name = 'Apple Pie'
+  );
 
 -- UPDATE
 /* 1.We want to add the current_quantity to the product_units table. 
@@ -128,6 +204,15 @@ Finally, make sure you have a WHERE statement to update the right row,
 	you'll need to use product_units.product_id to refer to the correct row within the product_units table. 
 When you have all of these components, you can run the update statement. */
 
+ALTER TABLE product_units ADD COLUMN current_quantity INT;
 
+UPDATE product_units
+SET current_quantity = COALESCE((
+    SELECT quantity
+    FROM vendor_inventory vi
+    WHERE vi.product_id = product_units.product_id
+    ORDER BY market_date DESC, vendor_id
+    LIMIT 1
+), 0);
 
 

03_instructional_team/sqbpro_originals/module_3.sqbpro

@@ -105,19 +105,6 @@ Filter to number of purchases between 300 and 500  */
 
 /* 2. What is the name of the vendor who sells pie */
 
-</sql><sql name="CTE">/* MODULE 3 */
-/* Common Table Expression (CTE) */
-
-
-/* 1. Calculate sales per vendor per day */
-SELECT 
-
-
-
-
-
-/* ... re-aggregate the daily sales for each WEEK instead now  */
-
 </sql><sql name="temp_table">/* MODULE 3 */
 /* Temp Tables */
 
@@ -142,6 +129,21 @@ CREATE TABLE temp.new_vendor_inventory AS
 /* 2. put the previous table into another temp table, e.g. as temp.new_new_vendor_inventory  */
 
 
+</sql><sql name="CTE">/* MODULE 3 */
+/* Common Table Expression (CTE) */
+
+
+/* 1. Calculate sales per vendor per day */
+SELECT 
+
+
+
+
+
+/* ... re-aggregate the daily sales for each WEEK instead now  */
+
+
+
 </sql><sql name="dates">/* MODULE 3 */
 /* Date functions */
 

03_instructional_team/sqbpro_originals/module_5.sqbpro

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="UTF-8"?><sqlb_project><window><main_tabs open="structure browser pragmas query" current="3"/></window><tab_structure><column_width id="0" width="300"/><column_width id="1" width="0"/><column_width id="2" width="100"/><column_width id="3" width="12168"/><column_width id="4" width="0"/><expanded_item id="0" parent="1"/><expanded_item id="1" parent="1"/><expanded_item id="2" parent="1"/><expanded_item id="3" parent="1"/></tab_structure><tab_browse><table title="booth" custom_title="0" dock_id="2" table="4,5:mainbooth"/><dock_state state="000000ff00000000fd000000010000000200000536000003a5fc0100000002fb000000160064006f0063006b00420072006f00770073006500310100000000ffffffff0000000000000000fb000000160064006f0063006b00420072006f00770073006500320100000000000005360000012300ffffff000005360000000000000004000000040000000800000008fc00000000"/><default_encoding codec=""/><browse_table_settings><table schema="main" name="booth" show_row_id="0" encoding="" plot_x_axis="" unlock_view_pk="_rowid_" freeze_columns="0"><sort/><column_widths><column index="1" value="136"/><column index="2" value="164"/><column index="3" value="300"/><column index="4" value="108"/></column_widths><filter_values/><conditional_formats/><row_id_formats/><display_formats/><hidden_columns/><plot_y_axes/><global_filter/></table></browse_table_settings></tab_browse><tab_sql><sql name="INSERT_UPDATE_DELETE">/* MODULE 5 */
+<?xml version="1.0" encoding="UTF-8"?><sqlb_project><window><main_tabs open="structure browser pragmas query" current="3"/></window><tab_structure><column_width id="0" width="300"/><column_width id="1" width="0"/><column_width id="2" width="100"/><column_width id="3" width="12168"/><column_width id="4" width="0"/><expanded_item id="0" parent="1"/><expanded_item id="1" parent="1"/><expanded_item id="2" parent="1"/><expanded_item id="3" parent="1"/></tab_structure><tab_browse><table title="booth" custom_title="0" dock_id="2" table="4,5:mainbooth"/><dock_state state="000000ff00000000fd0000000100000002000004a4000003a5fc0100000002fb000000160064006f0063006b00420072006f00770073006500310100000000ffffffff0000000000000000fb000000160064006f0063006b00420072006f00770073006500320100000000000004a40000012300ffffff000004a40000000000000004000000040000000800000008fc00000000"/><default_encoding codec=""/><browse_table_settings/></tab_browse><tab_sql><sql name="INSERT_UPDATE_DELETE*">/* MODULE 5 */
 /* INSERT UPDATE DELETE */
 
 
@@ -45,30 +45,18 @@ CREATE TEMP TABLE product_expanded AS
 
 
 
-</sql><sql name="update_statements_for_view">/* MODULE 5 */
-/* UPDATE statements for view */
+</sql><sql name="dynamic_view">/* MODULE 5 */
+/* DYNAMIC VIEW */
 
 
-/* 1. SET market_date equal to today for new_customer_purchases */
 
 
 
 
-/* 2. Add today's info to the market_date_info 
 
-we need to add 
-1. today's date
-2. today's day
-3. today's week number
-4. today's year
 
-INSERT INTO market_date_info
-VALUES('....','....','....','....','8:00 AM','2:00 PM','nothing interesting','Summer','25','28',0,0);
 
-*/
-
-</sql><sql name="dynamic_view">/* MODULE 5 */
-/* DYNAMIC VIEW */
+/* spoilers below */
 
 
 
@@ -78,7 +66,6 @@ VALUES('....','....','....','....','8:00 AM','2:00 PM','nothing interesting','Su
 
 
 
-/* spoilers below */
 
 
 
@@ -87,24 +74,37 @@ VALUES('....','....','....','....','8:00 AM','2:00 PM','nothing interesting','Su
 
 
 
+-- THIS ONLY WORKS IF YOU HAVE DONE THE PROPER STEPS FOR IMPORTING 
+-- 1) update new_customer_purchases to today
+-- 2) add the union 
+-- 3) add the where statement
+-- 4) update the market_date_info to include today
 
 
 
 
+</sql><sql name="update_statements_for_view">/* MODULE 5 */
+/* UPDATE statements for view */
 
 
+/* 1. SET market_date equal to today for new_customer_purchases */
 
 
 
--- THIS ONLY WORKS IF YOU HAVE DONE THE PROPER STEPS FOR IMPORTING 
--- 1) update new_customer_purchases to today
--- 2) add the union 
--- 3) add the where statement
--- 4) update the market_date_info to include today
 
+/* 2. Add today's info to the market_date_info 
 
+we need to add 
+1. today's date
+2. today's day
+3. today's week number
+4. today's year
 
+INSERT INTO market_date_info
+VALUES('....','....','....','....','8:00 AM','2:00 PM','nothing interesting','Summer','25','28',0,0);
 
+*/
+
 </sql><sql name="CROSS_JOIN">/* MODULE 5 */
 /* CROSS  JOIN */
 

04_this_cohort/custom_slides/markdown/slides_01.Rmd

@@ -203,7 +203,7 @@ class: left, top, inverse
 ### Course Tools
 - [DB Browser for SQLite](https://sqlitebrowser.org/dl/): *Where we will write code*
 - [GitHub](https://github.com/UofT-DSI/sql): *Module Overview*
-- [Etherpad](https://pad.riseup.net/p/SQL_DSI_SGS_Oct2025): *Where we will keep track of session progress*
+- [Etherpad](https://pad.riseup.net/p/SQL_DSI_Nov2025): *Where we will keep track of session progress*
   - **Visit and complete the sign in prompt at the start every session**
 - [SQLite documentation](https://www.sqlite.org/index.html): *For SQL specific questions*
 - [DrawIO](https://www.drawio.com/) or [Lucid](https://www.lucidchart.com/pages/): *For Assignments*

04_this_cohort/custom_slides/markdown/slides_01.html

@@ -191,7 +191,7 @@
 ### Course Tools
 - [DB Browser for SQLite](https://sqlitebrowser.org/dl/): *Where we will write code*
 - [GitHub](https://github.com/UofT-DSI/sql): *Module Overview*
-- [Etherpad](https://pad.riseup.net/p/SQL_DSI_SGS_Oct2025): *Where we will keep track of session progress*
+- [Etherpad](https://pad.riseup.net/p/SQL_DSI_Nov2025): *Where we will keep track of session progress*
   - **Visit and complete the sign in prompt at the start every session**
 - [SQLite documentation](https://www.sqlite.org/index.html): *For SQL specific questions*
 - [DrawIO](https://www.drawio.com/) or [Lucid](https://www.lucidchart.com/pages/): *For Assignments*

04_this_cohort/live_code/Cohort_8/module_2/CASE_WHEN.sql

@@ -0,0 +1,31 @@
+/* MODULE 2 */
+/* CASE */
+
+
+SELECT *,
+/* 1. Add a CASE statement declaring which days vendors should come */ 
+CASE WHEN vendor_type = 'Fresh Focused' THEN 'Wednesday'
+	WHEN vendor_type = 'Prepared Foods' THEN 'Thursday'
+	ELSE 'Saturday'
+	END as day_of_specialty
+
+/* 2. Add another CASE statement for Pie Day */
+,CASE WHEN vendor_name = "Annie's Pies" -- double quotes will work just this once 
+	THEN 'Annie is the best'
+	END AS annie_is_queen
+
+
+/* 3. Add another CASE statement with an ELSE clause to handle rows evaluating to False */
+,CASE WHEN vendor_name LIKE '%pie%'
+THEN 'Wednesday'
+ELSE 'Friday' -- with this else, we get values for all the FALSE statements
+END AS pie_day
+
+
+/* 4. Experiment with selecting a different column instead of just a string value */
+,CASE WHEN vendor_type = 'Fresh Focused' THEN vendor_owner_first_name
+	WHEN vendor_type = 'Eggs & Meats' THEN vendor_owner_last_name
+	END as first_or_last
+
+
+FROM vendor