# MySQL study notes 18: mathematical functions _ MySQL

Source: Internet
Author: User
MySQL study note 18: mathematical functions bitsCN.com absolute value functions ABS (x) and circumference ratio functions PI ()
`mysql> SELECT ABS(0.5), ABS(-0.5), PI();+----------+-----------+----------+| ABS(0.5) | ABS(-0.5) | PI()     |+----------+-----------+----------+|      0.5 |       0.5 | 3.141593 |+----------+-----------+----------+1 row in set (0.00 sec)`

Square root function SQRT (x) and evaluate the remainder function MOD (x, y)
`mysql> SELECT SQRT(16), SQRT(3), MOD(13,4);+----------+--------------------+-----------+| SQRT(16) | SQRT(3)            | MOD(13,4) |+----------+--------------------+-----------+|        4 | 1.7320508075688772 |         1 |+----------+--------------------+-----------+1 row in set (0.00 sec)`

Take the entire function CEIL (x), CEILING (x), and FLOOR (x)
`mysql> SELECT CEIL(2.3), CEIL(-2.3), CEILING(2.3), CEILING(-2.3);+-----------+------------+--------------+---------------+| CEIL(2.3) | CEIL(-2.3) | CEILING(2.3) | CEILING(-2.3) |+-----------+------------+--------------+---------------+|         3 |         -2 |            3 |            -2 |+-----------+------------+--------------+---------------+1 row in set (0.00 sec)mysql> SELECT FLOOR(2.3), FLOOR(-2.3);+------------+-------------+| FLOOR(2.3) | FLOOR(-2.3) |+------------+-------------+|          2 |          -3 |+------------+-------------+1 row in set (0.00 sec)`

CEIL (x) and CEILING (x) return the smallest integer greater than or equal to x

FLOOR (x) returns the largest integer less than or equal to x.

Random number functions RAND () and RAND (x)
`mysql> SELECT RAND(), RAND(2), RAND(2);+--------------------+--------------------+--------------------+| RAND()             | RAND(2)            | RAND(2)            |+--------------------+--------------------+--------------------+| 0.8269294489425881 | 0.6555866465490187 | 0.6555866465490187 |+--------------------+--------------------+--------------------+1 row in set (0.00 sec)`

The loss of the two functions RAND () and RAND (x) returns 0 ~ Random number of 1

The difference is that the number returned by RAND () is completely random, while the value returned by RAND (x) is the same when x is the same.

Rounding functions ROUND (x), ROUND (x, y), and TRUNCATE (x, y)
`mysql> SELECT ROUND(2.3), ROUND(2.5), ROUND(2.53,1), ROUND(2.55,1);+------------+------------+---------------+---------------+| ROUND(2.3) | ROUND(2.5) | ROUND(2.53,1) | ROUND(2.55,1) |+------------+------------+---------------+---------------+|          2 |          3 |           2.5 |           2.6 |+------------+------------+---------------+---------------+1 row in set (0.00 sec)`

ROUND (x) returns the integer nearest to x, that is, rounding x.

ROUND (x, y) returns the value of x rounded to the y digit after the decimal point.

`mysql> SELECT TRUNCATE(2.53,1), TRUNCATE(2.55,1);+------------------+------------------+| TRUNCATE(2.53,1) | TRUNCATE(2.55,1) |+------------------+------------------+|              2.5 |              2.5 |+------------------+------------------+1 row in set (0.00 sec)`

TRUNCATE (x, y) returns the value of x which is retained to the y-digit after the decimal point. The rounding operation is not performed.

SIGN function SIGN (x)
`mysql> SELECT SIGN(-2), SIGN(0), SIGN(2);+----------+---------+---------+| SIGN(-2) | SIGN(0) | SIGN(2) |+----------+---------+---------+|       -1 |       0 |       1 |+----------+---------+---------+1 row in set (0.00 sec)`

SIGN (x) returns the x symbol.-1 is a negative number, 0 is not changed, and 1 is an integer.

POWER functions POW (x, y), POWER (x, y)
`mysql> SELECT POW(3,2), POWER(3,2);+----------+------------+| POW(3,2) | POWER(3,2) |+----------+------------+|        9 |          9 |+----------+------------+1 row in set (0.00 sec)`

BitsCN.com
Related Keywords:

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

## A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

• #### Sales Support

1 on 1 presale consultation

• #### After-Sales Support

24/7 Technical Support 6 Free Tickets per Quarter Faster Response

• Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.