date, date_format 을 사용한 날짜 비교

   date, date_format 을 사용한 날짜 비교

date, date_format 을 사용하여 날짜 계산, 날짜형변환 메서드를 알아보자

   DATE (expr)

먼저 DATE 함수는 표현식, 혹은 datetime 부분의 날짜부분을 추출한다.

Extracts the date part of the date or datetime expression expr.

mysql> SELECT DATE('2003-12-31 01:02:03'); -> '2003-12-31'

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date

   DATE_FORMAT( date, format )

지정된 문자열에 따라서 날짜값의 형식을 변환한다. 형식지정자 에서는 '%' 를 사용하는데 '%'는 형식지정자 문자 앞에 사용한다.

Formats the date value according to the format string.

The following specifiers may be used in the format string. The % character is required before format specifier characters.

Specifier	Description
%a	Abbreviated weekday name (Sun..Sat)
%b	Abbreviated month name (Jan..Dec)
%c	Month, numeric (0..12)
%D	Day of the month with English suffix (0th, 1st, 2nd, 3rd, …)
%d	Day of the month, numeric (00..31)
%e	Day of the month, numeric (0..31)
%f	Microseconds (000000..999999)
%H	Hour (00..23)
%h	Hour (01..12)
%I	Hour (01..12)
%i	Minutes, numeric (00..59)
%j	Day of year (001..366)
%k	Hour (0..23)
%l	Hour (1..12)
%M	Month name (January..December)
%m	Month, numeric (00..12)
%p	AM or PM
%r	Time, 12-hour (hh:mm:ss followed by AM or PM)
%S	Seconds (00..59)
%s	Seconds (00..59)
%T	Time, 24-hour (hh:mm:ss)
%U	Week (00..53), where Sunday is the first day of the week; WEEK() mode 0
%u	Week (00..53), where Monday is the first day of the week; WEEK() mode 1
%V	Week (01..53), where Sunday is the first day of the week; WEEK() mode 2; used with %X
%v	Week (01..53), where Monday is the first day of the week; WEEK() mode 3; used with %x
%W	Weekday name (Sunday..Saturday)
%w	Day of the week (0=Sunday..6=Saturday)
%X	Year for the week where Sunday is the first day of the week, numeric, four digits; used with %V
%x	Year for the week, where Monday is the first day of the week, numeric, four digits; used with %v
%Y	Year, numeric, four digits
%y	Year, numeric (two digits)
%%	A literal % character
%x	x, for any “x” not listed above

Specifier	Description

Ranges for the month and day specifiers begin with zero due to the fact that MySQL permits the storing of incomplete dates such as '2014-00-00'.

The language used for day and month names and abbreviations is controlled by the value of the lc_time_names system variable (Section 10.15, “MySQL Server Locale Support”).

For the %U, %u, %V, and %v specifiers, see the description of the WEEK() function for information about the mode values. The mode affects how week numbering occurs.

DATE_FORMAT() returns a string with a character set and collation given by character_set_connection and collation_connection so that it can return month and weekday names containing non-ASCII characters.

mysql> SELECT DATE_FORMAT('2009-10-04 22:23:00', '%W %M %Y');
        -> 'Sunday October 2009'
mysql> SELECT DATE_FORMAT('2007-10-04 22:23:00', '%H:%i:%s');
        -> '22:23:00'
mysql> SELECT DATE_FORMAT('1900-10-04 22:23:00',
    ->                 '%D %y %a %d %m %b %j');
        -> '4th 00 Thu 04 10 Oct 277'
mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00',
    ->                 '%H %k %I %r %T %S %w');
        -> '22 22 10 10:23:00 PM 22:23:00 00 6'
mysql> SELECT DATE_FORMAT('1999-01-01', '%X %V');
        -> '1998 52'
mysql> SELECT DATE_FORMAT('2006-06-00', '%d');
        -> '00'

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-format

   날짜범위 계산 SQL Query

WHERE ( DATE(A.date) >= DATE_FORMAT( '2018-08-01', '%Y-%m-01') AND DATE(A.date) <= LAST_DAY('2018-08-01') )