Commit 8e668c3c authored by paul@central.snake.net's avatar paul@central.snake.net
Browse files

manual.texi minor change log fixes 

manual.texi	fix age calculations in the tutorial section to
manual.texi	determine age in integer years and to account for
manual.texi	relative order of dates within calendar year.
parent 3fb423fe

Docs/manual.texi

+89 −73
Original line number Diff line number Diff line
@@ -13170,75 +13170,89 @@ MySQL provides several functions that you can use to perform 
calculations on dates, for example, to calculate ages or extract

parts of dates.













To determine how many years old each of your pets is, compute age as the













difference between the birth date and the current date.  Do this by













converting the two dates to days, take the difference, and divide by 365 (the













number of days in a year):

























@example













mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 FROM pet;













+----------+-------------------------------------+













| name     | (TO_DAYS(NOW())-TO_DAYS(birth))/365 |













+----------+-------------------------------------+













| Fluffy   |                                6.15 |













| Claws    |                                5.04 |













| Buffy    |                                9.88 |













| Fang     |                                8.59 |













| Bowser   |                                9.58 |













| Chirpy   |                                0.55 |













| Whistler |                                1.30 |













| Slim     |                                2.92 |













| Puffball |                                0.00 |













+----------+-------------------------------------+













@end example

























Although the query works, there are some things about it that could be













improved.  First, the result could be scanned more easily if the rows were













presented in some order.  Second, the heading for the age column isn't very













To determine how many years old each of your pets is, compute the













difference in the year part of the current date and the birth date, then













subtract one if the current date occurs earlier in the calendar year than













the birth date.  The following query shows, for each pet, the birth date,













the current date, and the age in years.

























@example













mysql> SELECT name, birth, CURRENT_DATE,













    -> (YEAR(CURRENT_DATE)-YEAR(birth))













    -> - (RIGHT(CURRENT_DATE,5)<RIGHT(birth,5))













    -> AS age













    -> FROM pet;













+----------+------------+--------------+------+













| name     | birth      | CURRENT_DATE | age  |













+----------+------------+--------------+------+













| Fluffy   | 1993-02-04 | 2001-08-29   |    8 |













| Claws    | 1994-03-17 | 2001-08-29   |    7 |













| Buffy    | 1989-05-13 | 2001-08-29   |   12 |













| Fang     | 1990-08-27 | 2001-08-29   |   11 |













| Bowser   | 1989-08-31 | 2001-08-29   |   11 |













| Chirpy   | 1998-09-11 | 2001-08-29   |    2 |













| Whistler | 1997-12-09 | 2001-08-29   |    3 |













| Slim     | 1996-04-29 | 2001-08-29   |    5 |













| Puffball | 1999-03-30 | 2001-08-29   |    2 |













+----------+------------+--------------+------+













@end example

























Here, @code{YEAR()} pulls out the year part of a date and @code{RIGHT()}













pulls off the rightmost five characters that represent the @code{MM-DD}













(calendar year) part of the date.  The part of the expression that













compares the @code{MM-DD} values evaluates to 1 or 0, which adjusts the













year difference down a year if @code{CURRENT_DATE} occurs earlier in













the year than @code{birth}.  The full expression is somewhat ungainly,













so an alias (@code{age}) is used to make the output column label more















meaningful.



























The first problem can be handled by adding an @code{ORDER BY name} clause to













sort the output by name.  To deal with the column heading, provide a name for













the column so that a different label appears in the output (this is called a













column alias):













The query works, but the result could be scanned more easily if the rows













were presented in some order.  This can be done by adding an @code{ORDER













BY name} clause to sort the output by name:





























@example













mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 AS age













mysql> SELECT name, birth, CURRENT_DATE,













    -> (YEAR(CURRENT_DATE)-YEAR(birth))













    -> - (RIGHT(CURRENT_DATE,5)<RIGHT(birth,5))













    -> AS age















    -> FROM pet ORDER BY name;













+----------+------+













| name     | age  |













+----------+------+













| Bowser   | 9.58 |













| Buffy    | 9.88 |













| Chirpy   | 0.55 |













| Claws    | 5.04 |













| Fang     | 8.59 |













| Fluffy   | 6.15 |













| Puffball | 0.00 |













| Slim     | 2.92 |













| Whistler | 1.30 |













+----------+------+













+----------+------------+--------------+------+













| name     | birth      | CURRENT_DATE | age  |













+----------+------------+--------------+------+













| Bowser   | 1989-08-31 | 2001-08-29   |   11 |













| Buffy    | 1989-05-13 | 2001-08-29   |   12 |













| Chirpy   | 1998-09-11 | 2001-08-29   |    2 |













| Claws    | 1994-03-17 | 2001-08-29   |    7 |













| Fang     | 1990-08-27 | 2001-08-29   |   11 |













| Fluffy   | 1993-02-04 | 2001-08-29   |    8 |













| Puffball | 1999-03-30 | 2001-08-29   |    2 |













| Slim     | 1996-04-29 | 2001-08-29   |    5 |













| Whistler | 1997-12-09 | 2001-08-29   |    3 |













+----------+------------+--------------+------+















@end example





























To sort the output by @code{age} rather than @code{name}, just use a















different @code{ORDER BY} clause:





























@example













mysql>  SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 AS age













mysql> SELECT name, birth, CURRENT_DATE,













    -> (YEAR(CURRENT_DATE)-YEAR(birth))













    -> - (RIGHT(CURRENT_DATE,5)<RIGHT(birth,5))













    -> AS age















    -> FROM pet ORDER BY age;













+----------+------+













| name     | age  |













+----------+------+













| Puffball | 0.00 |













| Chirpy   | 0.55 |













| Whistler | 1.30 |













| Slim     | 2.92 |













| Claws    | 5.04 |













| Fluffy   | 6.15 |













| Fang     | 8.59 |













| Bowser   | 9.58 |













| Buffy    | 9.88 |













+----------+------+













+----------+------------+--------------+------+













| name     | birth      | CURRENT_DATE | age  |













+----------+------------+--------------+------+













| Chirpy   | 1998-09-11 | 2001-08-29   |    2 |













| Puffball | 1999-03-30 | 2001-08-29   |    2 |













| Whistler | 1997-12-09 | 2001-08-29   |    3 |













| Slim     | 1996-04-29 | 2001-08-29   |    5 |













| Claws    | 1994-03-17 | 2001-08-29   |    7 |













| Fluffy   | 1993-02-04 | 2001-08-29   |    8 |













| Fang     | 1990-08-27 | 2001-08-29   |   11 |













| Bowser   | 1989-08-31 | 2001-08-29   |   11 |













| Buffy    | 1989-05-13 | 2001-08-29   |   12 |













+----------+------------+--------------+------+















@end example





























A similar query can be used to determine age at death for animals that have









@@ -13248,12 +13262,14 @@ values, compute the difference between the @code{death} and @code{birth}













values:





























@example













mysql>  SELECT name, birth, death, (TO_DAYS(death)-TO_DAYS(birth))/365 AS age













mysql> SELECT name, birth, death,













    -> (YEAR(death)-YEAR(birth)) - (RIGHT(death,5)<RIGHT(birth,5))













    -> AS age















    -> FROM pet WHERE death IS NOT NULL ORDER BY age;















+--------+------------+------------+------+















| name   | birth      | death      | age  |















+--------+------------+------------+------+













| Bowser | 1989-08-31 | 1995-07-29 | 5.91 |













| Bowser | 1989-08-31 | 1995-07-29 |    5 |















+--------+------------+------------+------+















@end example
























@@ -13328,7 +13344,7 @@ mysql> SELECT name, birth FROM pet



























Note that @code{MONTH} returns a number between 1 and 12. And















@code{MOD(something,12)} returns a number between 0 and 11. So the













addition has to be after the @code{MOD()} otherwise we would go from













addition has to be after the @code{MOD()}, otherwise we would go from















November (11) to January (1).






































@@ -46696,35 +46712,35 @@ not yet 100% confident in this code.













@appendixsubsec Changes in release 3.23.42















@itemize @bullet















@item













Enforce that all tables in a @code{MERGE} table comes from the same













Enforce that all tables in a @code{MERGE} table come from the same















database.















@item















Fixed bug with @code{LOAD DATA INFILE} and transactional tables.















@item















Fix bug when using @code{INSERT DELAYED} with wrong column definition.















@item













Fixed coredump during REPAIR of some particulary broken tables.













Fixed coredump during @code{REPAIR} of some particularly broken tables.















@item















Fixed bug in @code{InnoDB} and @code{AUTO_INCREMENT} columns.















@item













Fixed critical bug in @code{InnoDB} and @code{BLOB}'s.  If one has used













@code{BLOB}'s larger than 8K in an @code{InnoDB} table one must dump













the table with @code{mysqldump}, drop it and restore it from the dump.













Fixed critical bug in @code{InnoDB} and @code{BLOB} columns.  If one has













used @code{BLOB} columns larger than 8K in an @code{InnoDB} table, one must













dump the table with @code{mysqldump}, drop it and restore it from the dump.















@item















Applied large patch for OS/2 from Yuri Dario.















@item













Fixed problem with InnoDB when one could get the error @code{Can't













Fixed problem with @code{InnoDB} when one could get the error @code{Can't















execute the given command...} even when one didn't have an active















transaction.















@item













Applied some minor fixes that concerns Gemini.













Applied some minor fixes that concern Gemini.















@item















Use real arithmetic operations even in integer context if not















all arguments are integers. (Fixes uncommon bug in some integer













context).













contexts).















@item













Don't force everything to lower cases on windows. (To fix problem













with windows and @code{ALTER TABLE}).  Now @code{--lower_case_names}













Don't force everything to lower cases on Windows. (To fix problem













with Windows and @code{ALTER TABLE}).  Now @code{--lower_case_names}















also works on Unix.















@item















Fixed that automatic rollback that is done when thread end doesn't lock









@@ -46740,7 +46756,7 @@ Added option @code{--sql-mode=option[,option[,option]]}.













@xref{Command-line options}.















@item















Fixed possible problem with @code{shutdown} on Solaris where the













@code{.pid} file wasn't deleted.













@file{.pid} file wasn't deleted.















@item















InnoDB now supports < 4 GB rows. The former limit was 8000 bytes.















@item