stored procedures and functions

Author: ptyadana

Complete SQL Mastery - Mosh/09.Stored Procedures and Functions.sql

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+/**************************************/
+/* Stored Procedures                  */
+/**************************************/
+DELIMITER $$
+CREATE PROCEDURE get_clients()
+BEGIN
+	SELECT * FROM clients;
+END $$
+DELIMITER ;
+
+/**************************************/
+/* Call Stored Procedures             */
+/**************************************/
+CALL get_clients();
+
+
+/* get_invoices_with_balance to return all the invoices with balance > 0 */
+DROP PROCEDURE IF EXISTS get_invoices_with_balance;
+
+DELIMITER $$
+CREATE PROCEDURE get_invoices_with_balance()
+BEGIN
+	SELECT *
+	FROM invoices
+	WHERE (invoice_total - payment_total) > 0;
+END $$
+DELIMITER ;
+
+CALL get_invoices_with_balance();
+
+/**************************************/
+/* DROP Stored Procedures             */
+/**************************************/
+
+DROP PROCEDURE IF EXISTS get_clients;
+
+
+/**************************************/
+/* Parameters                         */
+/**************************************/
+DROP PROCEDURE IF EXISTS get_client_by_state;
+
+DELIMITER $$
+CREATE PROCEDURE get_client_by_state(p_state CHAR(2))
+BEGIN
+	SELECT * FROM clients
+    WHERE state = p_state;
+END $$
+DELIMITER ;
+
+CALL get_client_by_state('NY');
+
+
+/* exercise */
+/* return invoices for a given client */
+
+DROP PROCEDURE IF EXISTS get_invoices_by_client;
+
+DELIMITER $$
+CREATE PROCEDURE get_invoices_by_client(p_client_name VARCHAR(50))
+BEGIN
+	SELECT * FROM invoices i
+    JOIN clients c ON c.client_id = i.invoice_id
+    WHERE c.name = p_client_name;
+END $$
+DELIMITER ;
+
+CALL get_invoices_by_client('Myworks');
+
+/**************************************/
+/* Parameters with DEFAULT values     */
+/**************************************/
+
+-- set the state to CA if there is no parameters given
+
+DROP PROCEDURE IF EXISTS get_client_by_state;
+
+DELIMITER $$
+CREATE PROCEDURE get_client_by_state(p_state CHAR(2))
+BEGIN
+	IF p_state IS NULL THEN
+		SET p_state = 'CA';
+	END IF;
+    
+	SELECT * FROM clients
+    WHERE state = p_state;
+END $$
+DELIMITER ;
+
+CALL get_client_by_state(NULL);
+
+-- get all clients,  if there is no parameters given 
+
+DROP PROCEDURE IF EXISTS get_client_by_state;
+
+DELIMITER $$
+CREATE PROCEDURE get_client_by_state(p_state CHAR(2))
+BEGIN
+	SELECT * FROM clients
+    WHERE state = IFNULL(p_state, state);
+END $$
+DELIMITER ;
+
+CALL get_client_by_state(NULL);
+
+/* Exercise */
+/*stored procedure get_payments with two parameters
+	client_id INT(4),
+    payment_method_id TINYINT(1) => 0-255
+
+parameters are optional and if not given, get all info
+*/
+DROP PROCEDURE IF EXISTS get_payments;
+
+DELIMITER $$
+CREATE PROCEDURE get_payments(p_client_id INT(4), p_payment_method_id TINYINT(1))
+BEGIN
+	SELECT * FROM payments
+    WHERE client_id = IFNULL(p_client_id, client_id)
+    AND payment_method = IFNULL(p_payment_method_id, payment_method);
+END $$
+DELIMITER ;
+
+CALL get_payments(5,2);
+CALL get_payments(5,NULL);
+CALL get_payments(NULL,1);
+CALL get_payments(NULL,NULL);
+
+
+/**************************************/
+/* Parameters Validation              */
+/**************************************/
+DROP PROCEDURE IF EXISTS make_payment;
+
+DELIMITER $$
+CREATE PROCEDURE make_payment(invoice_id INT, payment_amount DECIMAL(9,2), payment_date DATE)
+BEGIN
+	IF payment_amount <= 0 THEN
+		SIGNAL SQLSTATE '22003' 
+			SET MESSAGE_TEXT = 'Invalid Payment Amount';
+	END IF;
+         
+	UPDATE invoices i
+    SET i.invoice_amount = payment_amount,
+		i.payment_date = payment_date
+	WHERE i.invoice_id = invoice_id;
+END $$
+DELIMITER ;
+
+-- Testing
+CALL mosh_sql_invoicing.make_payment(1, -345, '2020-05-01');
+
+
+/**************************************/
+/* Output Parameters                  */
+/**************************************/
+
+/*get unpaid invoices for a client */
+DROP PROCEDURE IF EXISTS get_unpaid_invoices_for_client;
+
+DELIMITER $$
+CREATE PROCEDURE get_unpaid_invoices_for_client(client_id INT, OUT number_of_unpaid_invoices INT, OUT total_unpaid_amount INT)
+BEGIN
+	SELECT COUNT(*), SUM(invoice_total)
+		INTO number_of_unpaid_invoices, total_unpaid_amount
+    FROM invoices i
+    WHERE i.client_id = client_id
+    AND payment_total = 0;
+END $$
+DELIMITER ;
+
+-- testing
+set @number_of_unpaid_invoices = 0;
+set @total_unpaid_amount = 0;
+call mosh_sql_invoicing.get_unpaid_invoices_for_client(3, @number_of_unpaid_invoices, @total_unpaid_amount);
+select @number_of_unpaid_invoices, @total_unpaid_amount;
+
+
+/**************************************/
+/* Variables                          */
+/**************************************/
+
+-- User or Session Variables
+set @total_unpaid_amount = 0;
+
+-- Local Variables
+DELIMITER $$
+CREATE PROCEDURE get_risk_factor()
+BEGIN
+	DECLARE risk_factor DECIMAL(9,2) DEFAULT 0;
+    DECLARE invoices_total DECIMAL(9,2);
+    DECLARE invoice_count INT;
+    
+    SELECT COUNT(*), SUM(invoice_total)
+		INTO invoices_total, invoice_count
+    FROM invoices;
+    
+    SET risk_factor = invoices_total / invoice_count * 5;
+    
+    SELECT risk_factor;
+END $$
+DELIMITER ;
+
+
+CALL get_risk_factor();
+
+/***********************************************************/
+
+/**************************************/
+/* Functions                          */
+/**************************************/
+DROP FUNCTION IF EXISTS func_get_risk_factor_for_client;
+
+DELIMITER $$
+CREATE FUNCTION func_get_risk_factor_for_client(client_id INT)
+	RETURNS INTEGER
+    READS SQL DATA
+BEGIN
+	DECLARE risk_factor DECIMAL(9,2) DEFAULT 0;
+    DECLARE invoices_total DECIMAL(9,2);
+    DECLARE invoice_count INT;
+    
+    SELECT COUNT(*), SUM(invoice_total)
+		INTO invoices_total, invoice_count
+    FROM invoices i
+    WHERE i.client_id = client_id;
+    
+    SET risk_factor = invoices_total / invoice_count * 5;
+    
+    RETURN IFNULL(risk_factor,0);
+END $$
+DELIMITER ;
+
+-- Testing
+SELECT client_id, name, func_get_risk_factor_for_client(client_id) AS risk_factor
+FROM clients;