Database SQL language 06 single line function

String functions and mathematical functions

SELECT	ABS(-8);	/* The absolute value */
SELECT	CEILING(9.4); /* Rounding up */
SELECT	FLOOR(9.4);	/* Rounding down */
SELECT	RAND();	/* random number , Return to one 0-1 Random number between */
SELECT	SIGN(0); /* Symbolic function :  A negative number returns -1, A positive number returns 1,0 return 0*/

SELECT CHAR_LENGTH(' Crazy God says persistence can succeed '); /* Returns the number of characters contained in a string */
SELECT CONCAT(' I ',' Love ',' Program ');	/* Merge strings , Parameters can have multiple */
SELECT INSERT(' I love programming. helloworld',1,2,' Super love ');	/* Replace string , Start from a certain position to replace   Change a certain length */
SELECT LOWER('KuangShen'); /* A lowercase letter */
SELECT UPPER('KuangShen'); /* Capitalization */
SELECT LEFT('hello,world',5);	/* Cut from the left */
SELECT RIGHT('hello,world',5);	/* Cut from the right */
SELECT REPLACE(' Crazy God says persistence can succeed ',' insist ',' Strive ');	/* Replace string */
SELECT SUBSTR(' Crazy God says persistence can succeed ',4,6); /* Intercepting string , Start and length */
SELECT REVERSE(' Crazy God says persistence can succeed '); /* reverse 

--  Look up the students surnamed Zhou , Change to Zou 
SELECT REPLACE(studentname,' Zhou ',' Zou ') AS  New name 
FROM student WHERE studentname LIKE ' Zhou %';

Date and time functions

SELECT CURRENT_DATE();	/* Get current date */
SELECT CURDATE();	/* Get current date */
SELECT NOW();	/* Get the current date and time */
SELECT LOCALTIME();	/* Get the current date and time */
SELECT SYSDATE();	/* Get the current date and time */

--  Get date , Minutes and seconds 
SELECT YEAR(NOW());
SELECT MONTH(NOW());
SELECT DAY(NOW());
SELECT HOUR(NOW());
SELECT MINUTE(NOW());
SELECT SECOND(NOW());

– Numerical function

abs(x)	--  The absolute value  abs(-10.9) = 10
format(x, d)	--  Format the number of thousandths  format(1234567.456, 2) = 1,234,567.46
ceil(x)		--  Rounding up  ceil(10.1) = 11
floor(x)	--  Rounding down  floor (10.1) = 10
round(x)	--  Round to the nearest whole 
mod(m, n)	-- m%n m mod n  Seeking remainder  10%3=1
pi()	--  Get the pi 
pow(m, n)	-- m^n
sqrt(x)	--  Arithmetical square root 
rand()	--  random number 
truncate(x, d)	--  Intercept d Decimal place 

– Time date function

now(), current_timestamp();	--  Current date time 
current_date();	--  The current date 
current_time();	--  current time 
date('yyyy-mm-dd hh:ii:ss');	--  Get the date part 
time('yyyy-mm-dd hh:ii:ss');	--  Get the time part 
date_format('yyyy-mm-dd hh:ii:ss', '%d %y %a %d %m %b %j');	--  Format time 
unix_timestamp();	--  get unix Time stamp 
from_unixtime();	--  Get the time from the time stamp 

– String function

length(string)	-- string length , byte 
char_length(string)	-- string Characters of 
substring(str, position [,length])	--  from str Of position Start , take length Characters 
replace(str ,search_str ,replace_str)	--  stay str of use replace_str Replace search_str
instr(string ,substring)	--  return substring First time in string Where in 
concat(string [,...])	--  Connection string 
charset(str)	--  Returns the string character set 
lcase(string)	--  Convert to lowercase 
left(string, length)	--  from string2 From the left side of length Characters 
load_file(file_name)	--  Read from file 
locate(substring, string [,start_position])	--  Same as instr, But you can specify the starting position 
lpad(string, length, pad)	--  Repeat pad Add to string start , Until the string length is length
ltrim(string)	--  Remove the front space 
repeat(string, count)	--  repeat count Time 
rpad(string, length, pad)	-- stay str After use pad Add , Until the length is length
rtrim(string)	--  Remove back-end space 
strcmp(string1 ,string2)	--  Compare the size of two strings character by character 
--  Aggregate functions 
count()
sum();
max();
min();
avg();
group_concat()