Mysql Common functions （ Summary ）

One 、 Common digital processing functions

Common digital processing functions	The name of the function	perform sql	Return results
ABS(x)	return x The absolute value of	SELECT ABS(-1);	1
AVG(expression)	averaging	select AXG(age) from student	Returns the average age
CEIL(x)	Greater than x Minimum integer of	SELECT CEIL(1.5);	2
CEILING(x)	Greater than x Or equal to x Minimum integer of	SELECT CEILING(1.5);	2
FLOOR(x)	Less than x Minimum integer of	SELECT FLOOR(1.5);	1
MAX(age)	Maximum	SELECT MAX(age) AS maxAge FROM Student;	Return to maximum age
POWER(x,y)	return x Of y Power	SELECT POWER(2,3);	return 2 Of 3 Power
RAND()	return 0 To 1 The random number
SUM(expression)	Returns the sum of the specified fields	SELECT SUM(age) FROM Student;	Age sum
SQRT(x)	return x The square root of	SELECT SQRT(25);	return 5
TRUNCATE(x,y)	The number x Retain y position	SELECT TRUNCATE(1.23456,3);	return 1.234
GREATEST(expr1, expr2, …)	Returns the maximum value in the list	SELECT GREATEST(3, 12, 34, 8, 25);	return 34
LEAST(expr1, expr2, …)	Returns the minimum value in the list	SELECT LEAST(3, 12, 34, 8, 25);	return 3

Two 、 Common date functions

1、CURDATE()/CURRENT_DATE() Return current date

SELECT CURDATE();
SELECT CURRENT_DATE();
----  Return return current date 

2、CURRENT_TIME()/CURTIME() Return current time

SELECT CURRENT_TIME();
----  return 17:40:45

3、CURRENT_TIMESTAMP() Returns the current date and time

SELECT CURRENT_TIMESTAMP();
----  return 2022-07-26 17:41:32

4、ADDDATE(d,n) Calculate start date d add n The date of day

SELECT ADDDATE("2017-06-15", INTERVAL 10 DAY);
----  return 2017-06-25

5、ADDTIME(t,n) Time t add n The second time

SELECT ADDTIME('2011-11-11 11:11:11', 5);
----  return 2011-11-11 11:11:16

6、DATE() Extract a date value from a date or datetime expression

SELECT DATE("2017-06-15 11:11:16");
----  return 2017-06-15

7、DAY(d) Returns the date value d The date part of

SELECT DAY("2017-06-15");