Homeworks

03_homework/homework_1.md

@@ -76,3 +76,4 @@ Please do not pick the exact same tables that I have already diagramed. For exam
 	-  ![01_farmers_market_conceptual_model.png](./images/01_farmers_market_conceptual_model.png)
 - The column names can be found in a few spots (DB Schema window in the bottom right, the Database Structure tab in the main window by expanding each table entry, at the top of the Browse Data tab in the main window)
 
+![Fredy Rincon's Logical Data Model](image.png)

03_homework/homework_2.md

@@ -21,3 +21,6 @@
 
 # JOIN
 1. Write a query that `INNER JOIN`s the `vendor` table to the `vendor_booth_assignments` table on the `vendor_id` field they both have in common, and sorts the result by `vendor_name`, then `market_date`.
+
+[Link to Fredy's homework_2.sql](homework_2.sql)
+[Link to Fredy's homework_2.txt](homework_2.txt)

03_homework/homework_2.sql

@@ -0,0 +1,65 @@
+-- SELECT 1: Query to return everything in the customer table:
+
+SELECT * FROM customer;
+
+-- SELECT 2: Query to display all ten columns and ten rows from the customer table, sorted by customer_last_name and then customer_first_name:
+
+SELECT * 
+FROM customer 
+ORDER BY customer_last_name, customer_first_name 
+LIMIT 10;
+
+
+-- WHERE 1: Query to return all customer purchases of product IDs 4 and 9:
+
+SELECT * 
+FROM customer_purchases 
+WHERE product_id IN (4, 9);
+
+
+-- WHERE 2a: Query to return all customer purchases and a new calculated column 'price', filtered by vendor IDs between 8 and 10 using AND:
+
+SELECT *, (quantity * cost_to_customer_per_qty) AS price 
+FROM customer_purchases 
+WHERE vendor_id >= 8 AND vendor_id <= 10;
+
+
+-- WHERE 2b: Query to return all customer purchases and a new calculated column 'price', filtered by vendor IDs between 8 and 10 using BETWEEN:
+
+SELECT *, (quantity * cost_to_customer_per_qty) AS price 
+FROM customer_purchases 
+WHERE vendor_id BETWEEN 8 AND 10;
+
+
+-- CASE 1: Query to output product_id, product_name, and add a column called prod_qty_type_condensed:
+
+SELECT product_id, product_name, 
+CASE 
+    WHEN product_qty_type = 'unit' THEN 'unit' 
+    ELSE 'bulk' 
+END AS prod_qty_type_condensed 
+FROM product;
+
+
+-- CASE 2: Query to add a column called pepper_flag:
+
+SELECT product_id, product_name, 
+CASE 
+    WHEN product_qty_type = 'unit' THEN 'unit' 
+    ELSE 'bulk' 
+END AS prod_qty_type_condensed, 
+CASE 
+    WHEN LOWER(product_name) LIKE '%pepper%' THEN 1 
+    ELSE 0 
+END AS pepper_flag 
+FROM product;
+
+
+-- JOIN: Query to INNER JOIN the vendor table to the vendor_booth_assignments table on the vendor_id field and sort by vendor_name, then market_date:
+
+SELECT *
+FROM vendor
+INNER JOIN vendor_booth_assignments
+ON vendor.vendor_id = vendor_booth_assignments.vendor_id
+ORDER BY vendor.vendor_name, vendor_booth_assignments.market_date;
+

03_homework/homework_2.txt

@@ -0,0 +1,65 @@
+-- SELECT 1: Query to return everything in the customer table:
+
+SELECT * FROM customer;
+
+-- SELECT 2: Query to display all ten columns and ten rows from the customer table, sorted by customer_last_name and then customer_first_name:
+
+SELECT * 
+FROM customer 
+ORDER BY customer_last_name, customer_first_name 
+LIMIT 10;
+
+
+-- WHERE 1: Query to return all customer purchases of product IDs 4 and 9:
+
+SELECT * 
+FROM customer_purchases 
+WHERE product_id IN (4, 9);
+
+
+-- WHERE 2a: Query to return all customer purchases and a new calculated column 'price', filtered by vendor IDs between 8 and 10 using AND:
+
+SELECT *, (quantity * cost_to_customer_per_qty) AS price 
+FROM customer_purchases 
+WHERE vendor_id >= 8 AND vendor_id <= 10;
+
+
+-- WHERE 2b: Query to return all customer purchases and a new calculated column 'price', filtered by vendor IDs between 8 and 10 using BETWEEN:
+
+SELECT *, (quantity * cost_to_customer_per_qty) AS price 
+FROM customer_purchases 
+WHERE vendor_id BETWEEN 8 AND 10;
+
+
+-- CASE 1: Query to output product_id, product_name, and add a column called prod_qty_type_condensed:
+
+SELECT product_id, product_name, 
+CASE 
+    WHEN product_qty_type = 'unit' THEN 'unit' 
+    ELSE 'bulk' 
+END AS prod_qty_type_condensed 
+FROM product;
+
+
+-- CASE 2: Query to add a column called pepper_flag:
+
+SELECT product_id, product_name, 
+CASE 
+    WHEN product_qty_type = 'unit' THEN 'unit' 
+    ELSE 'bulk' 
+END AS prod_qty_type_condensed, 
+CASE 
+    WHEN LOWER(product_name) LIKE '%pepper%' THEN 1 
+    ELSE 0 
+END AS pepper_flag 
+FROM product;
+
+
+-- JOIN: Query to INNER JOIN the vendor table to the vendor_booth_assignments table on the vendor_id field and sort by vendor_name, then market_date:
+
+SELECT *
+FROM vendor
+INNER JOIN vendor_booth_assignments
+ON vendor.vendor_id = vendor_booth_assignments.vendor_id
+ORDER BY vendor.vendor_name, vendor_booth_assignments.market_date;
+

03_homework/homework_3.md

@@ -22,3 +22,5 @@ To insert the new row use VALUES, specifying the value you want for each column:
 2. Using the previous query as a base, determine how much money each customer spent in April 2019. Remember that money spent is `quantity*cost_to_customer_per_qty`.
 **HINTS**: you will need to AGGREGATE, GROUP BY, and filter...but remember, STRFTIME returns a STRING for your WHERE statement!!
 
+[Fredy's SQL Homework_3](homework_3.sql)
+

03_homework/homework_3.sql

@@ -0,0 +1,33 @@
+--Aggregate Query: Counting Vendor Booth Assignments
+SELECT vendor_id, COUNT(*) AS booth_assignment_count
+FROM vendor_booth_assignments
+GROUP BY vendor_id;
+
+--Aggregate Query: Customers Spending More Than $2000
+SELECT c.customer_id, c.customer_first_name, c.customer_last_name, SUM(cp.quantity * cp.cost_to_customer_per_qty) AS total_spent
+FROM customer c
+JOIN customer_purchases cp ON c.customer_id = cp.customer_id
+GROUP BY c.customer_id, c.customer_first_name, c.customer_last_name
+HAVING total_spent > 2000
+ORDER BY c.customer_last_name, c.customer_first_name;
+
+--Temp Table: Insert New Vendor
+CREATE TEMPORARY TABLE new_vendor AS
+SELECT *
+FROM vendor;
+
+INSERT INTO new_vendor (vendor_id, vendor_name, vendor_type, vendor_owner_first_name, vendor_owner_last_name)
+VALUES (10, 'Thomass Superfood Store', 'Fresh Focused', 'Thomas', 'Rosenthal');
+
+--Date Query: Extract Month and Year
+SELECT customer_id, strftime('%m', market_date) AS month, strftime('%Y', market_date) AS year
+FROM customer_purchases;
+
+--Date Query: Customer Spending in April 2019
+SELECT customer_id, SUM(quantity * cost_to_customer_per_qty) AS total_spent
+FROM customer_purchases
+WHERE strftime('%m', market_date) = '04' AND strftime('%Y', market_date) = '2019'
+GROUP BY customer_id;
+--FREDY RINCON
+--uoft-dsi-c3-homework_3-20240517
+--uoft-dsi-c3-sql_homework_3-20240517

03_homework/homework_4.md

@@ -43,3 +43,5 @@ You can either display all rows in the customer_purchases table, with the counte
 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.
 
 **HINT**: There are a possibly a few ways to do this query, but if you're struggling, try the following: 1) Create a CTE/Temp Table to find sales values grouped dates; 2) Create another CTE/Temp table with a rank windowed function on the previous query to create "best day" and "worst day"; 3) Query the second temp table twice, once for the best day, once for the worst day, with a UNION binding them. 
+
+[Homework_4.sql](homework_4.sql)

03_homework/homework_4.sql

@@ -0,0 +1,143 @@
+-- COALESCE
+/* 1. Our favourite manager wants a detailed long list of products, but is afraid of tables! 
+We tell them, no problem! We can produce a list with all of the appropriate details. 
+
+Using the following syntax you create our super cool and not at all needy manager a list:
+
+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. 
+
+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.) */
+
+SELECT 
+    COALESCE(product_name, '') || ', ' || 
+    COALESCE(product_size, '') || ' (' || 
+    COALESCE(product_qty_type, 'unit') || ')'
+FROM product;
+
+
+
+--Windowed Functions
+/* 1. Write a query that selects from the customer_purchases table and numbers each customer’s  
+visits to the farmer’s market (labeling each market date with a different number). 
+Each customer’s first visit is labeled 1, second visit is labeled 2, etc. 
+
+You can either display all rows in the customer_purchases table, with the counter changing on
+each new market date for each customer, or select only the unique market dates per customer 
+(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;
+
+
+/* 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_number
+    FROM 
+        customer_purchases
+)
+SELECT * 
+FROM ranked_visits
+WHERE visit_number = 1;
+
+
+/* 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 
+    customer_id, 
+    product_id, 
+    quantity, 
+    COUNT(*) OVER (PARTITION BY customer_id, product_id) as purchase_count
+FROM 
+    customer_purchases;
+
+
+
+-- String manipulations
+/* 1. Some product names in the product table have descriptions like "Jar" or "Organic". 
+These are separated from the product name with a hyphen. 
+Create a column using SUBSTR (and a couple of other commands) that captures these, but is otherwise NULL. 
+Remove any trailing or leading whitespaces. Don't just use a case statement for each product! 
+
+| product_name               | description |
+|----------------------------|-------------|
+| Habanero Peppers - Organic | Organic     |
+
+Hint: you might need to use INSTR(product_name,'-') to find the hyphens. INSTR will help split the column. */
+
+SELECT 
+    product_name,
+    TRIM(SUBSTR(product_name, INSTR(product_name, '-') + 2)) as description
+FROM 
+    product
+WHERE 
+    INSTR(product_name, '-') > 0;
+
+-- UNION
+/* 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.
+
+HINT: There are a possibly a few ways to do this query, but if you're struggling, try the following: 
+1) Create a CTE/Temp Table to find sales values grouped dates; 
+2) Create another CTE/Temp table with a rank windowed function on the previous query to create 
+"best day" and "worst day"; 
+3) Query the second temp table twice, once for the best day, once for the worst day, 
+with a UNION binding them. */
+
+WITH sales_by_date AS (
+    SELECT 
+        market_date, 
+        SUM(quantity * cost_to_customer_per_qty) as total_sales
+    FROM 
+        customer_purchases
+    GROUP BY 
+        market_date
+),
+ranked_sales AS (
+    SELECT 
+        market_date, 
+        total_sales, 
+        RANK() OVER (ORDER BY total_sales DESC) as sales_rank_desc,
+        RANK() OVER (ORDER BY total_sales ASC) as sales_rank_asc
+    FROM 
+        sales_by_date
+)
+SELECT 
+    market_date, 
+    total_sales, 
+    'Highest Sales' as sales_type
+FROM 
+    ranked_sales
+WHERE 
+    sales_rank_desc = 1
+
+UNION
+
+SELECT 
+    market_date, 
+    total_sales, 
+    'Lowest Sales' as sales_type
+FROM 
+    ranked_sales
+WHERE 
+    sales_rank_asc = 1;
+
+
+

03_homework/homework_5.md

@@ -33,5 +33,6 @@ Then, using `UPDATE`, change the current_quantity equal to the **last** `quantit
 
 **HINT**: This one is pretty hard. First, determine how to get the "last" quantity per product. Second, coalesce null values to 0 (if you don't have null values, figure out how to rearrange your query so you do.) Third, `SET current_quantity = (...your select statement...)`, remembering that WHERE can only accommodate one column. 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.
 
+[Homework_5.sql](homework_5.sql)