add retrieve data JOINS, Union

Author: ptyadana

Complete SQL Mastery - Mosh/03.Retrieving Data From Multiple Tables.sql

@@ -0,0 +1,143 @@
+/******************************************/
+/*       JOINS                            */
+/******************************************/
+
+SELECT oi.order_id,p.name,oi.quantity,oi.unit_price
+FROM order_items oi
+JOIN products p ON p.product_id = oi.product_id;
+
+
+/******************************************/
+/*       SELF JOINS                       */
+/******************************************/
+USE mosh_sql_hr;
+
+SELECT * FROM employees
+LIMIT 5;
+
+/*employee and his/her manager */
+SELECT e1.employee_id, e1.first_name, e1.last_name, 
+	COALESCE(CONCAT(e2.first_name,e2.last_name), 'Top Manager') AS manager
+FROM employees e1
+LEFT JOIN employees e2 ON e1.reports_to = e2.employee_id;
+
+
+/******************************************/
+/*       Joining Multiple Tables          */
+/******************************************/
+USE mosh_sql_store;
+
+SELECT o.order_id, o.order_date, c.first_name, c.last_name, os.name
+FROM orders o
+JOIN customers c ON c.customer_id = o.customer_id
+JOIN order_statuses os ON os.order_status_id = o.status;
+
+/*payment and customer details*/
+USE mosh_sql_invoicing;
+
+SELECT c.client_id, c.name,p.invoice_id,p.date,p.amount,pm.name
+FROM payments p
+JOIN payment_methods pm ON pm.payment_method_id = p.payment_method
+JOIN clients c ON c.client_id = p.client_id;
+
+
+/******************************************/
+/*       Implicit Join                    */
+/******************************************/
+
+SELECT c.client_id, c.name,p.invoice_id,p.date,p.amount,pm.name
+FROM payments p, payment_methods pm, clients c
+WHERE pm.payment_method_id = p.payment_method
+AND c.client_id = p.client_id;
+
+/******************************************/
+/*       Outer Joins                      */
+/******************************************/
+USE mosh_sql_store;
+
+SELECT c.customer_id, c.first_name,c.last_name,o.order_id
+FROM customers c
+LEFT JOIN orders o ON o.customer_id = c.customer_id
+ORDER BY 1;
+
+/*products and how many time it has been ordered*/
+SELECT p.product_id, p.name, oi.quantity
+FROM products p
+LEFT JOIN order_items oi ON oi.product_id = p.product_id;
+
+/* product which has never been ordered */
+SELECT p.product_id, p.name, oi.quantity
+FROM products p
+LEFT JOIN order_items oi ON oi.product_id = p.product_id
+WHERE oi.product_id IS NULL;
+
+/* order, customer name, status where status is in processed or shipped */
+SELECT o.order_date, o.order_id, c.first_name, s.name, os.name
+FROM orders o
+JOIN customers c ON o.customer_id = c.customer_id
+LEFT JOIN shippers s ON s.shipper_id = o.shipper_id
+LEFT JOIN order_statuses os ON os.order_status_id = o.status;
+
+/******************************************/
+/*       USING                            */
+/******************************************/
+SELECT *
+FROM order_items oi
+JOIN order_item_notes oin
+	USING(order_id,product_id);
+    
+
+/*client and payment methods */
+USE mosh_sql_invoicing;
+
+SELECT p.date, c.name, p.amount, pm.name
+FROM payments p
+JOIN clients c USING (client_id)
+JOIN payment_methods pm ON pm.payment_method_id = p.payment_method;
+
+
+/******************************************************************/
+/*       Natural Joins                                            */
+/* it allows sql engine to pick up the keys by itself for joining */
+/******************************************************************/
+USE mosh_sql_store;
+
+SELECT o.order_id, c.first_name
+FROM orders o
+NATURAL JOIN customers c;
+
+
+/******************************************************************/
+/*       CORSS JOIN                                               */
+/******************************************************************/
+/* cross join between shippers and products using implicit and explict*/
+SELECT s.name, p.name
+FROM shippers s , products p;
+
+SELECT s.name, p.name
+FROM shippers s
+CROSS JOIN products p;
+
+
+/******************************************************************/
+/*       UNION                                                    */
+/******************************************************************/
+
+SELECT *, 'Active' AS status
+	FROM orders
+	WHERE order_date >= CURDATE() - INTERVAL 1 YEAR
+UNION
+SELECT *, 'Archived' AS status
+	FROM orders
+	WHERE order_date < CURDATE() - INTERVAL 1 YEAR;
+    
+
+/* customer and point status */
+SELECT customer_id, first_name, points,
+	CASE
+		WHEN points > 3000 THEN 'Gold'
+        WHEN points >= 2000 AND points <= 3000 THEN 'Silver'
+        ELSE 'Bronze'
+    END AS type
+FROM customers
+ORDER BY 2;