SELECT user_id, CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS name

FROM Users

ORDER BY 1

SELECT patient_id, patient_name, conditions

FROM Patients

WHERE conditions REGEXP '\\bDIAB1'

DELETE p1

FROM Person p1, Person p2

WHERE p1.email = p2.email AND p1.id > p2.id

SELECT MAX(salary) AS SecondHighestSalary

FROM Employee

WHERE salary < (

SELECT MAX(salary)

FROM Employee

);

SELECT sell_date, count( DISTINCT product ) AS num_sold , GROUP_CONCAT( DISTINCT product ORDER BY product ASC separator ',' ) AS products

FROM Activities GROUP BY sell_date

ORDER BY sell_date ASC

SELECT p.product_name AS product_name, sum(o.unit) AS unit FROM Products p

JOIN Orders o USING (product_id)

WHERE YEAR(o.order_date)='2020' AND MONTH(o.order_date)='02'

GROUP BY p.product_id

HAVING SUM(o.unit)>=100

SELECT user_id, name, mail

FROM Users

WHERE mail REGEXP '^[a-zA-Z][a-zA-Z0-9_.-]*@leetcode[.]com$'