essential mysql functions

Author: ptyadana

Complete SQL Mastery - Mosh/07.Essential MySQL Functions.sql

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+/****************************************/
+/*     Numeric Functions                */
+/****************************************/
+
+SELECT ROUND(7.58,1);
+
+SELECT TRUNCATE(7.58374,3);
+
+SELECT CEILING (7.58374);
+SELECT CEILING (7.1);
+
+SELECT FLOOR(7.6);
+
+SELECT ABS(-5.4);
+
+SELECT RAND();
+
+/****************************************/
+/*     String Functions                 */
+/****************************************/
+
+SELECT LENGTH('hello');
+
+SELECT UPPER('hello');
+
+SELECT lower('Hello');
+
+SELECT LTRIM('    Hello');
+
+SELECT RTRIM('Hello    ');
+
+SELECT TRIM('     I am so AWESOME!    ');
+
+SELECT LEFT('Kindergarten',4);
+
+SELECT RIGHT('Kindergarten',6);
+
+SELECT SUBSTRING('Kindergarten', 3, 5);
+
+SELECT LOCATE('n', 'Kindergarten');
+
+SELECT LOCATE('y', 'Kindergarten');
+SELECT LOCATE('garten', 'Kindergarten');
+
+SELECT REPLACE('Kindergarten', 'garten', 'garden');
+
+SELECT CONCAT('John', ' ' ,'Snow');
+
+/****************************************/
+/*     Date Functions                  */
+/****************************************/
+SELECT NOW(), CURDATE(), CURTIME(), YEAR(NOW()), MONTH(NOW()), DATE(NOW()), 
+	DAYNAME(NOW()), MONTHNAME(NOW());
+    
+SELECT EXTRACT(DAY FROM NOW()), EXTRACT(MONTH FROM NOW()), EXTRACT(YEAR FROM NOW());
+
+USE mosh_sql_store;
+
+SELECT *
+FROM orders
+WHERE YEAR(order_date) > YEAR(NOW());
+
+/****************************************/
+/*     Formatting Date Times            */
+/****************************************/
+
+SELECT DATE_FORMAT(NOW(), '%D %M %Y');
+
+SELECT DATE_FORMAT(NOW(), '%d %m %y');
+
+SELECT TIME_FORMAT(NOW(), '%H %m %p');
+
+/****************************************/
+/*     Calcualting Date Times           */
+/****************************************/
+
+-- add 1 day
+SELECT DATE_ADD(NOW(), INTERVAL 1 DAY);
+
+-- subtract 1 year
+SELECT DATE_ADD(NOW(), INTERVAL -1 YEAR);
+
+SELECT DATEDIFF('2019-01-01', '2020-01-01');
+
+-- number of seconds since Mid Night
+SELECT TIME_TO_SEC('09:00') - TIME_TO_SEC('09:02');
+
+/****************************************/
+/*     IFNULL AND COALESCE              */
+/****************************************/
+
+USE mosh_sql_store;
+
+SELECT order_id, customer_id, order_date, status,
+	IFNULL(shipped_date,'NOT ASSIGNED') AS shipped_date,
+    COALESCE(shipper_id, comments, 'PENDING') AS shipper
+FROM orders;
+
+/* customer name, phone*/
+SELECT CONCAT(first_name, ' ', last_name) AS customer_name,
+	COALESCE(phone,'UNKNOWN') AS phone
+FROM customers;
+
+
+/****************************************/
+/*     IF function                      */
+/****************************************/
+/*
+   IF (expression, first, second)
+*/
+
+SELECT order_id, order_date,
+	IF(YEAR(order_date) >= YEAR(NOW()), 'Active', 'Archived') AS status
+FROM orders;
+
+/* product and its ordered frequncy category */
+SELECT p.product_id, p.name, COUNT(p.product_id) AS times_of_orders,
+	IF(COUNT(p.product_id) > 1, 'Many times', 'Once') AS frequency_category
+FROM products p
+JOIN order_items oi ON oi.product_id = p.product_id
+GROUP BY 1;
+
+/****************************************/
+/*     CASE function                    */
+/****************************************/
+
+SELECT order_id, order_date,
+	CASE
+		WHEN YEAR(order_date) >= YEAR(NOW()) THEN 'Active'
+        WHEN YEAR(order_date) = YEAR(DATE_ADD(NOW(), INTERVAL -1 YEAR)) THEN 'Last Year'
+        ELSE 'Archived'
+    END AS status
+FROM orders;