sql assignment1 - Sultan Mehmood

02_activities/assignments/Cohort_8/assignment1.sql

@@ -5,16 +5,31 @@
 --SELECT
 /* 1. Write a query that returns everything in the customer table. */
 
+SELECT *
+FROM customer
 
 
 /* 2. Write a query that displays all of the columns and 10 rows from the cus- tomer table, 
 sorted by customer_last_name, then customer_first_ name. */
 
+SELECT *
 
+FROM customer
+
+ORDER By 
+	customer_last_name, customer_first_name
+LIMIT 10
 
 --WHERE
 /* 1. Write a query that returns all customer purchases of product IDs 4 and 9. */
 
+SELECT *
+FROM customer_purchases
+
+WHERE 
+	product_id = 4
+AND product_id = 9
+
 
 
 /*2. Write a query that returns all customer purchases and a new calculated column 'price' (quantity * cost_to_customer_per_qty), 
@@ -24,9 +39,29 @@ filtered by customer IDs between 8 and 10 (inclusive) using either:
 */
 -- option 1
 
+SELECT
+quantity,
+customer_id,
+cost_to_customer_per_qty,
+quantity * cost_to_customer_per_qty AS price
+
+FROM customer_purchases
+
+WHERE 
+	customer_id >= 8 AND customer_id <= 10;
+
 
 -- option 2
 
+SELECT
+quantity,
+customer_id,
+cost_to_customer_per_qty,
+quantity * cost_to_customer_per_qty AS price
+
+FROM customer_purchases
+
+WHERE customer_id BETWEEN 8 AND 10;
 
 
 --CASE
@@ -35,19 +70,48 @@ Using the product table, write a query that outputs the product_id and product_n
 columns and add a column called prod_qty_type_condensed that displays the word “unit” 
 if the product_qty_type is “unit,” and otherwise displays the word “bulk.” */
 
+SELECT
+	product_id,
+	product_name,
 
+CASE 
+	WHEN product_qty_type = 'unit' THEN 'unit'
+	ELSE 'bulk'
+END AS product_qty_type_condensed
+
+FROM product;
 
 /* 2. We want to flag all of the different types of pepper products that are sold at the market. 
 add a column to the previous query called pepper_flag that outputs a 1 if the product_name 
 contains the word “pepper” (regardless of capitalization), and otherwise outputs 0. */
 
+SELECT
+    product_id,
+    product_name,
+CASE
+    WHEN product_qty_type = 'unit' THEN 'unit'
+    ELSE 'bulk'
+    END AS prod_qty_type_condensed,
+CASE
+    WHEN product_name LIKE '%pepper%' THEN 1
+    ELSE 0
+    END AS pepper_flag
+
+FROM product;
 
 
 --JOIN
 /* 1. Write a query that INNER JOINs 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. */
 
+SELECT * 
+
+FROM vendor
+
+INNER JOIN vendor_booth_assignments
+	ON vendor.vendor_id = vendor_booth_assignments.vendor_id
 
+	ORDER BY vendor_name, market_date;
 
 
 /* SECTION 3 */
@@ -56,15 +120,33 @@ vendor_id field they both have in common, and sorts the result by vendor_name, t
 /* 1. Write a query that determines how many times each vendor has rented a booth 
 at the farmer’s market by counting the vendor booth assignments per vendor_id. */
 
+SELECT 
+vendor_id,
+COUNT(*) as num_of_booth
 
+FROM vendor_booth_assignments
+
+GROUP BY vendor_id;
 
 /* 2. The Farmer’s Market Customer Appreciation Committee wants to give a bumper 
 sticker to everyone who has ever spent more than $2000 at the market. Write a query that generates a list 
 of customers for them to give stickers to, sorted by last name, then first name. 
 
 HINT: This query requires you to join two tables, use an aggregate function, and use the HAVING keyword. */
 
+SELECT *
+	,SUM(quantity*cost_to_customer_per_qty) AS total_spend 
+
+FROM customer_purchases AS cp
+	INNER JOIN customer AS c 
+	ON cp.customer_id = c.customer_id
+
+GROUP BY customer_first_name, customer_last_name
+
+HAVING total_spend > 2000
 
+ORDER BY
+customer_last_name, customer_first_name;
 
 --Temp Table
 /* 1. Insert the original vendor table into a temp.new_vendor and then add a 10th vendor: 
@@ -78,19 +160,18 @@ When inserting the new vendor, you need to appropriately align the columns to be
 VALUES(col1,col2,col3,col4,col5) 
 */
 
+DROP TABLE IF EXISTS temp.new_vendor;
 
+CREATE TABLE temp.new_vendor AS
 
--- Date
-/*1. Get the customer_id, month, and year (in separate columns) of every purchase in the customer_purchases table.
+SELECT *
 
-HINT: you might need to search for strfrtime modifers sqlite on the web to know what the modifers for month 
-and year are! */
+FROM vendor;
 
+INSERT INTO temp.new_vendor (vendor_id, vendor_name, vendor_type, vendor_owner_first_name, vendor_owner_last_name)
+VALUES (10, 'Thomas Superfood Store', 'Fresh Focused Store', 'Thomas', 'Rental');
 
 
-/* 2. Using the previous query as a base, determine how much money each customer spent in April 2022. 
-Remember that money spent is quantity*cost_to_customer_per_qty. 
+SELECT * FROM new_vendor;
 
-HINTS: you will need to AGGREGATE, GROUP BY, and filter...
-but remember, STRFTIME returns a STRING for your WHERE statement!! */
 

02_activities/assignments/Cohort_8/assignment2.sql

@@ -6,22 +6,17 @@
 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 
+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 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. 
-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 *
+,NULLIF(product_size,'NULL') as product_size_null
+,coalesce(NULLIF(product_size,'NULL'),'') as balnk_product_size
 
+,NULLIF(product_qty_type,'NULL') as product_qty_type_null
+,coalesce(NULLIF(product_qty_type,'NULL'),'unit') as unit_product_qty_type
 
+FROM product;
 
 
 --Windowed Functions
@@ -34,18 +29,36 @@ 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,
+    DENSE_RANK() OVER (PARTITION BY customer_id ORDER BY market_date ASC) 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. */
 
 
+SELECT * FROM (
+    SELECT 
+        customer_id,
+        market_date,
+        DENSE_RANK() OVER (PARTITION BY customer_id ORDER BY market_date DESC) as visit_number
+    FROM customer_purchases
+) 
+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,
+    COUNT(product_id) 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". 
@@ -58,11 +71,14 @@ Remove any trailing or leading whitespaces. Don't just use a case statement for
 | Habanero Peppers - Organic | Organic     |
 
 Hint: you might need to use INSTR(product_name,'-') to find the hyphens. INSTR will help split the column. */
-
-
-
 /* 2. Filter the query to show any product_size value that contain a number with REGEXP. */
 
+SELECT *, 
+CASE WHEN INSTR(product_name,'-') > 0
+  THEN LTRIM(RTRIM(SUBSTR(product_name,INSTR(product_name,'-')+1)))
+  ELSE NULL END AS description
+FROM product
+WHERE product_size REGEXP '[0-9]';
 
 
 -- UNION
@@ -71,10 +87,30 @@ Hint: you might need to use INSTR(product_name,'-') to find the hyphens. INSTR w
 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"; 
+"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 DailySales AS (
+    SELECT 
+        market_date, 
+        SUM(quantity * cost_to_customer_per_qty) as total_sales
+    FROM customer_purchases
+    GROUP BY market_date
+)
+SELECT * FROM (
+    SELECT market_date, total_sales, 'Highest Sales' as category
+    FROM DailySales
+    ORDER BY total_sales DESC
+    LIMIT 1
+)
+UNION
+SELECT * FROM (
+    SELECT market_date, total_sales, 'Lowest Sales' as category
+    FROM DailySales
+    ORDER BY total_sales ASC
+    LIMIT 1
+);
 
 
 
@@ -92,25 +128,48 @@ How many customers are there (y).
 Before your final group by you should have the product of those two queries (x*y).  */
 
 
+WITH CustomerCount AS (
+    SELECT COUNT(DISTINCT customer_id) as cust_count FROM customer
+),
+UniqueProducts AS (
+    SELECT DISTINCT vendor_id, product_id, original_price 
+    FROM vendor_inventory
+)
+SELECT 
+    v.vendor_name,
+    p.product_name,
+    (up.original_price * 5 * cc.cust_count) as potential_revenue
+FROM UniqueProducts up
+JOIN vendor v ON up.vendor_id = v.vendor_id
+JOIN product p ON up.product_id = p.product_id
+CROSS JOIN CustomerCount cc;
+
 
 -- 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`. */
 
+CREATE TABLE product_units AS
+SELECT *, CURRENT_TIMESTAMP as snapshot_timestamp
+FROM product
+WHERE product_qty_type = 'unit';
 
+-- Next, insert a new row (e.g., a new Apple Pie record).
 
-/*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 (product_id, product_name, product_size, product_category_id, product_qty_type, snapshot_timestamp)
+VALUES (9999, 'Apple Pie', 'Large', 1, 'unit', CURRENT_TIMESTAMP);
 
 
 -- 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 product_id != 999;
 
 
 -- UPDATE
@@ -131,5 +190,22 @@ Finally, make sure you have a WHERE statement to update the right row,
 When you have all of these components, you can run the update statement. */
 
 
+-- Step 1: Add the column
+ALTER TABLE product_units
+ADD current_quantity INT;
 
 
+-- Step 2: Update the column with the most recent inventory quantity
+UPDATE product_units
+SET current_quantity = (
+    SELECT COALESCE(quantity, 0)
+    FROM vendor_inventory vi
+    WHERE vi.product_id = product_units.product_id
+    ORDER BY market_date DESC
+    LIMIT 1
+)
+WHERE EXISTS (
+    SELECT 1
+    FROM vendor_inventory vi
+    WHERE vi.product_id = product_units.product_id
+);