Several MySQL functions commonly used in projects

1.find_in_set function
Find_in_set (str,strlist); STR is a string strlist is a string list--a string that has more than one child chain "," separated by
There are a number of situations:
Null find_in_set (NULL, "A.STR") returns NULL when NULL or strlist is NULL
B. If the first argument is a constant string and the second is a type set column, the Find_in_set () function is optimized to use the bit calculation
C.str not in strlist or empty string returns 0 str with "," will error
Select Find_in_set (' 2 ', ' + '); return 2
Select Find_in_set (' 6 ', ' 1 '); Returns 0
SELECT Find_in_set (' B ', ' a,b,c,d ') str is b in the second position in strlist so return 2

D. Special case: SELECT * from user where Find_in_set (ID, "1,3,4,5,8");
Similar to select * from user where ID in (1,3,4,5,8);
2.date_format (Date,format) formatted date
%a Abbreviated Week name
%b Abbreviated month name
%c month, numeric
%d days of the month with English prefixes
%d months of the day, value (00-31)
%e Month Day, value (0-31)
%f μs
%h hours (00-23)
%h hours (01-12)
%i hours (01-12)
%i min, numeric (00-59)
Day of the%j year (001-366)
%k hours (0-23)
%l hours (1-12)
%m Month Name
%m month, value (00-12)
%pam or PM
%r time, 12-hour (Hh:mm:ss AM or PM)
%s seconds (00-59)
%s seconds (00-59)
%t time, 24-hour (HH:MM:SS)
%u week (00-53) Sunday is the first day of the week
%u week (00-53) Monday is the first day of the week
%v Week (01-53) Sunday is the first day of the week, with%x
%v Week (01-53) Monday is the first day of the week, with%x
%w Week Name
%w Day of the week (0= Sunday, 6 = Saturday)
%x year, of which Sunday was the first day of the week, 4-bit, with%V used
%x year, of which Monday was the first day of the week, 4-bit, with%v used
%y year, 4 people
%y year, 2 people
3.from_unixtime and Unix_timestamp are the opposite time functions
From_unixtime is to convert the specified format of seconds to a date SELECT from_unixtime (1511280000, '%y year%m month%d ') November 22, 2017
Unix_timestamp is the conversion of a date into seconds SELECT unix_timestamp (' 2017-11-22 '); 1511280000

Several MySQL functions commonly used in projects