WL#1264 "Per-thread time zone support infrastructure".

Added basic per-thread time zone functionality (based on public
domain elsie-code). Now user can select current time zone
(from the list of time zones described in system tables).
All NOW-like functions honor this time zone, values of TIMESTAMP
type are interpreted as values in this time zone, so now
our TIMESTAMP type behaves similar to Oracle's TIMESTAMP WITH
LOCAL TIME ZONE (or proper PostgresSQL type).
  
WL#1266 "CONVERT_TZ() - basic time with time zone conversion 
function".
  
Fixed problems described in Bug #2336 (Different number of warnings 
when inserting bad datetime as string or as number). This required
reworking of datetime realted warning hadling (they now generated 
at Field object level not in conversion functions).
  
Optimization: Now Field class descendants use table->in_use member
instead of current_thd macro.


include/my_global.h:
  Added macro for reading of 32-bit ints stored in network order from
  unaligned memory location.
include/mysqld_error.h:
  Added error-code for invalid timestamp warning and error-code
  for wrong or unknown time zone specification.
libmysqld/Makefile.am:
  Added main per-thread time zone support file to libmysqld
libmysqld/lib_sql.cc:
  Added initialization of time zones infrastructure to embedded server.
mysql-test/r/connect.result:
  Updated test result since now mysql database contains more
  system tables.
mysql-test/r/date_formats.result:
  Now when truncation occurs during conversion to datetime value we are producing Warnings 
  instead of Notes. Also we are giving more clear warnings about this in some cases.
mysql-test/r/func_sapdb.result:
  New warnings about truncation occured during conversion to datetime value added due
  their better handling.
mysql-test/r/func_time.result:
  New warnings about truncation occured during conversion to datetime value added due
  their better handling.
mysql-test/r/select.result:
  New warnings about truncation occured during conversion to datetime value added due
  their better handling. Also tweaked test a bit to made it less ambigious for reader.
mysql-test/r/system_mysql_db.result:
  Updated test result because new system tables holding time zone descriptions were 
  added.
mysql-test/r/timezone.result:
  Updated timezone.test to use new system variable which shows system time zone.
  Added test of warning which is produced if someone tries to store non-existing (due 
  falling into spring time-gap) datetime value into TIMESTAMP field.
mysql-test/r/type_datetime.result:
  Separated and extended test of values and warnings produced for bad values stored in 
  DATETTIME fields.
mysql-test/r/type_time.result:
  Now we are producing more consistent warning when we are truncating datetime value while
  storing it in TIME field.
mysql-test/r/type_timestamp.result:
  Separated and extended test of values and warnings produced for bad
  values stored in TIMESTAMP fields.
mysql-test/t/select.test:
  Updated test to make it less ambigous for reader.
mysql-test/t/timezone.test:
  Updated timezone.test to use new system variable which shows system time zone.
  Added test of warning which is produced if someone tries to store non-existing (due 
  falling into spring time-gap) datetime value into TIMESTAMP field.
mysql-test/t/type_datetime.test:
  Separated and extended test of values and warnings produced for bad
  values stored in DATETTIME fields.
mysql-test/t/type_timestamp.test:
  Separated and extended test of values and warnings produced for bad
  values stored in TIMESTAMP fields.
scripts/mysql_create_system_tables.sh:
  Added creation of tables with time zone descriptions.
  Also added descriptions of time zones used in tests.
scripts/mysql_fix_privilege_tables.sql:
  Added mysql.time_zone* tables family.
sql/Makefile.am:
  Added files implementing time zone support to server, also added
  rules for building of mysql_tzinfo_to_sql converter and test_time
  test.
sql/field.cc:
  Now we are using per-thread time zone for TIMESTAMP <-> whatever conversion.
  Fixed generation of warnings for datetime types (DATETIME/TIMESTAMP/DATE/...) and
  any other Field to datetime conversion (now we are generating warnings no in lower
  level functions like in str_to_TIME() but in Field methods. This allows generate
  better and more consistent warnings and to reuse code of str_to_TIME() outside of
  server).
  
  Added 3rd parameter to set_warning() method to be able to not increment cut fields
  but still produce a warning. Also added set_datetime_warning() family of auxiliary 
  methods which allow easier generate datetime related warnings.
  Also replaced occurences of current_thd with table->in_use member, added
  asserts for catching all places there we need to set table->in_use
  accordingly. Renamed fix_datetime() function to number_to_TIME() and
  moved it to sql/time.cc there it fits better.
sql/field.h:
  Added comment about places where we can use table->in_use member
  instead of current_thd.
  Added 3rd parameter to Field::set_warning() method and set_datetime_warning()
  family of methods.
sql/field_conv.cc:
  Field::set_warning() method with 2 arguments was replaced with more 
  generic set_warning() method with 3 arguments.
sql/ha_berkeley.cc:
  Now we set table->in_use for temporary tables so we have to use
  table->tmp_table for checking if table is temporary.
sql/item.cc:
  Replaced calls to str_to_time() and str_to_TIME() funcs with their warning
  generating analogs.
sql/item_create.cc:
  Added creation of CONVERT_TZ function as FUNC_ARG3.
sql/item_create.h:
  Added creation of CONVERT_TZ function as FUNC_ARG3.
sql/item_timefunc.cc:
  Added support of per-thread time zone to NOW-like and FROM_UNIXTIME,
  UNIX_TIMESTAMP functions. 
  Added support for CONVERT_TZ function.
  Removed call to str_to_timestamp function which caused non-optimal
  behavior in certain cases. Replaced calls to str_to_time() function 
  with its warning generating analog.
sql/item_timefunc.h:
  Added support of per-thread time zone to NOW-like and
  FROM_UNIXTIME, UNIX_TIMESTAMP functions.
  Added support of CONVERT_TZ function.
sql/lex.h:
  Added support of CONVERT_TZ function.
sql/log.cc:
  Added support for replication of statements depending on time zone.
sql/mysql_priv.h:
  Now including headers with per-thread time zone support functions
  and classes. Added portable replacement of time_t - my_time_t type. 
  Added time zone as one of query distinguishing parameters for
  query cache. 
  Fixed declarations of str_to_TIME, str_to_time and 
  my_system_gmt_sec (former my_gmt_sec) since now they have one more
  out parameter which informs about wrong datetime value or data 
  truncation during conversion.
  Added warning generating version of str_to_TIME() and str_to_time()
  functions.
  Thrown away str_to_datetime/timestamp functions since they are not
  needed any longer. Added number_to_TIME function.
sql/mysqld.cc:
  Added per-thread time zone support initialization.
  Added new startup parameter --default-time-zone.
sql/set_var.cc:
  Added support for per-thread time_zone variable.
  Renamed old timezone variable to system_time_zone.
sql/set_var.h:
  Added support for per-thread time_zone variable.
sql/share/czech/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/danish/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/dutch/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/english/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/estonian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/french/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/german/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/greek/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/hungarian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/italian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/japanese/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/korean/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/norwegian-ny/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/norwegian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/polish/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/portuguese/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/romanian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/russian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/serbian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/slovak/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/spanish/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/swedish/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/share/ukrainian/errmsg.txt:
  Added error message for barking when incorrect time zone name or
  specifiaction is provided and for warning about invalid TIMESTAMP
  values (e.g. falling into the spring time-gap).
sql/slave.cc:
  In order to support replication of statements using time zones in 4.1 we should 
  ensure that both master and slave have same default time zone.
sql/sql_base.cc:
  Now we are setting TABLE::in_use member for all tables (which assume
  calls to Field::store or val_ methods).
sql/sql_cache.cc:
  Added time zone as one more query distinguishing parameter
  for query cache.
sql/sql_class.cc:
  Added THD::time_zone_used variable indicating that this query
  uses per thread time zone.
sql/sql_class.h:
  Added per-thread time zone variable. Added THD::time_zone_used
  variable indicating that this query uses per thread time zone
  so if this is updating query the time zone should be logged to 
  binlog.
sql/sql_insert.cc:
  We should set TABLE::in_use member pointing to thread which is called
  INSERT DELAYED and not to worker thread.
sql/sql_load.cc:
  Field::set_warning() now has one more argument now.
sql/sql_parse.cc:
  Resetting THD::time_zone_used variable in the end of query
  processing.
sql/sql_select.cc:
  Now we are setting TABLE::in_use member for all tables (which assume
  calls to Field::store or val_ methods).
sql/sql_show.cc:
  Now using per thread time zone for extended show tables.
sql/time.cc:
  Added support for per-thread time zones for TIMESTAMP type and
  reworked generation of warnings for TIMESTAMP and DATETIME types.
  (Introduced new TIME_to_timestamp() function. Removed hours 
  normalisation from former my_gmt_sec() since it was not working 
  and not used anywhere now, but breaks parameter constness, added
  to this function generation of warning if we are falling in spring 
  time-gap. Removed str_to_timestamp and str_to_datetime functions 
  which are no longer used. Moved fix_datetime function from
  sql/field.cc to this file as number_to_TIME() function. Added
  out parameter for str_to_TIME and str_to_time functions which
  indicates if value was truncated during conversion, removed direct 
  generation of warnings from this functions.)
sql/unireg.cc:
  Now we are setting TABLE::in_use member for all tables (which assume
    calls to Field::store or val_ methods).
BitKeeper/etc/ignore:
  Added sql/test_time sql/mysql_tzinfo_to_sql libmysqld/tztime.cc to the ignore list

1 files changed, 246 insertions, 0 deletions

diff --git a/mysql-test/r/timezone2.result b/mysql-test/r/timezone2.result
new file mode 100644
index 00000000000..5361ff4ffe6
--- /dev/null
+++ b/mysql-test/r/timezone2.result
@@ -0,0 +1,246 @@
+drop table if exists t1;
+create table t1 (ts timestamp);
+set time_zone='+00:00';
+select unix_timestamp(utc_timestamp())-unix_timestamp(current_timestamp());
+unix_timestamp(utc_timestamp())-unix_timestamp(current_timestamp())
+0
+insert into t1 (ts) values ('2003-03-30 02:30:00');
+set time_zone='+10:30';
+select unix_timestamp(utc_timestamp())-unix_timestamp(current_timestamp());
+unix_timestamp(utc_timestamp())-unix_timestamp(current_timestamp())
+-37800
+insert into t1 (ts) values ('2003-03-30 02:30:00');
+set time_zone='-10:00';
+select unix_timestamp(utc_timestamp())-unix_timestamp(current_timestamp());
+unix_timestamp(utc_timestamp())-unix_timestamp(current_timestamp())
+36000
+insert into t1 (ts) values ('2003-03-30 02:30:00');
+select * from t1;
+ts
+2003-03-29 16:30:00
+2003-03-29 06:00:00
+2003-03-30 02:30:00
+drop table t1;
+select Name from mysql.time_zone_name where Name in 
+('UTC','Universal','MET','Europe/Moscow','leap/Europe/Moscow');
+Name
+Europe/Moscow
+leap/Europe/Moscow
+MET
+Universal
+UTC
+create table t1 (i int, ts timestamp);
+set time_zone='MET';
+insert into t1 (i, ts) values
+(unix_timestamp('2003-03-01 00:00:00'),'2003-03-01 00:00:00');
+insert into t1 (i, ts) values
+(unix_timestamp('2003-03-30 01:59:59'),'2003-03-30 01:59:59'),
+(unix_timestamp('2003-03-30 02:30:00'),'2003-03-30 02:30:00'),
+(unix_timestamp('2003-03-30 03:00:00'),'2003-03-30 03:00:00');
+Warnings:
+Warning	1299	Invalid TIMESTAMP value in column 'ts' at row 2
+insert into t1 (i, ts) values
+(unix_timestamp('2003-05-01 00:00:00'),'2003-05-01 00:00:00');
+insert into t1 (i, ts) values
+(unix_timestamp('2003-10-26 01:00:00'),'2003-10-26 01:00:00'),
+(unix_timestamp('2003-10-26 02:00:00'),'2003-10-26 02:00:00'),
+(unix_timestamp('2003-10-26 02:59:59'),'2003-10-26 02:59:59'),
+(unix_timestamp('2003-10-26 04:00:00'),'2003-10-26 04:00:00'),
+(unix_timestamp('2003-10-26 02:59:59'),'2003-10-26 02:59:59');
+set time_zone='UTC';
+select * from t1;
+i	ts
+1046473200	2003-02-28 23:00:00
+1048985999	2003-03-30 00:59:59
+1048986000	2003-03-30 01:00:00
+1048986000	2003-03-30 01:00:00
+1051740000	2003-04-30 22:00:00
+1067122800	2003-10-25 23:00:00
+1067126400	2003-10-26 00:00:00
+1067129999	2003-10-26 00:59:59
+1067137200	2003-10-26 03:00:00
+1067129999	2003-10-26 00:59:59
+delete from t1;
+set time_zone='Europe/Moscow';
+insert into t1 (i, ts) values
+(unix_timestamp('2004-01-01 00:00:00'),'2004-01-01 00:00:00'),
+(unix_timestamp('2004-03-28 02:30:00'),'2004-03-28 02:30:00'),
+(unix_timestamp('2004-08-01 00:00:00'),'2003-08-01 00:00:00'),
+(unix_timestamp('2004-10-31 02:30:00'),'2004-10-31 02:30:00');
+Warnings:
+Warning	1299	Invalid TIMESTAMP value in column 'ts' at row 2
+select * from t1;
+i	ts
+1072904400	2004-01-01 00:00:00
+1080428400	2004-03-28 03:00:00
+1091304000	2003-08-01 00:00:00
+1099175400	2004-10-31 02:30:00
+delete from t1;
+set time_zone='leap/Europe/Moscow';
+insert into t1 (i, ts) values
+(unix_timestamp('2004-01-01 00:00:00'),'2004-01-01 00:00:00'),
+(unix_timestamp('2004-03-28 02:30:00'),'2004-03-28 02:30:00'),
+(unix_timestamp('2004-08-01 00:00:00'),'2003-08-01 00:00:00'),
+(unix_timestamp('2004-10-31 02:30:00'),'2004-10-31 02:30:00');
+Warnings:
+Warning	1299	Invalid TIMESTAMP value in column 'ts' at row 2
+select * from t1;
+i	ts
+1072904422	2004-01-01 00:00:00
+1080428422	2004-03-28 03:00:00
+1091304022	2003-08-01 00:00:00
+1099175422	2004-10-31 02:30:00
+delete from t1;
+insert into t1 (i, ts) values
+(unix_timestamp('1981-07-01 03:59:59'),'1981-07-01 03:59:59'),
+(unix_timestamp('1981-07-01 04:00:00'),'1981-07-01 04:00:00');
+select * from t1;
+i	ts
+362793608	1981-07-01 03:59:59
+362793610	1981-07-01 04:00:00
+select from_unixtime(362793609);
+from_unixtime(362793609)
+1981-07-01 03:59:60
+drop table t1;
+create table t1 (ts timestamp);
+set time_zone='UTC';
+insert into t1 values ('0000-00-00 00:00:00'),('1969-12-31 23:59:59'),
+('1970-01-01 00:00:00'),('1970-01-01 00:00:01'),
+('2037-12-31 23:59:59'),('2038-01-01 00:00:00');
+Warnings:
+Warning	1264	Data truncated; out of range for column 'ts' at row 2
+Warning	1264	Data truncated; out of range for column 'ts' at row 3
+Warning	1264	Data truncated; out of range for column 'ts' at row 6
+select * from t1;
+ts
+0000-00-00 00:00:00
+0000-00-00 00:00:00
+0000-00-00 00:00:00
+1970-01-01 00:00:01
+2037-12-31 23:59:59
+0000-00-00 00:00:00
+delete from t1;
+set time_zone='MET';
+insert into t1 values ('0000-00-00 00:00:00'),('1970-01-01 00:30:00'),
+('1970-01-01 01:00:00'),('1970-01-01 01:00:01'),
+('2038-01-01 00:59:59'),('2038-01-01 01:00:00');
+Warnings:
+Warning	1264	Data truncated; out of range for column 'ts' at row 2
+Warning	1264	Data truncated; out of range for column 'ts' at row 3
+Warning	1264	Data truncated; out of range for column 'ts' at row 6
+select * from t1;
+ts
+0000-00-00 00:00:00
+0000-00-00 00:00:00
+0000-00-00 00:00:00
+1970-01-01 01:00:01
+2038-01-01 00:59:59
+0000-00-00 00:00:00
+delete from t1;
+set time_zone='+01:30';
+insert into t1 values ('0000-00-00 00:00:00'),('1970-01-01 01:00:00'),
+('1970-01-01 01:30:00'),('1970-01-01 01:30:01'),
+('2038-01-01 01:29:59'),('2038-01-01 01:30:00');
+Warnings:
+Warning	1264	Data truncated; out of range for column 'ts' at row 2
+Warning	1264	Data truncated; out of range for column 'ts' at row 3
+Warning	1264	Data truncated; out of range for column 'ts' at row 6
+select * from t1;
+ts
+0000-00-00 00:00:00
+0000-00-00 00:00:00
+0000-00-00 00:00:00
+1970-01-01 01:30:01
+2038-01-01 01:29:59
+0000-00-00 00:00:00
+drop table t1;
+show variables like 'time_zone';
+Variable_name	Value
+time_zone	+01:30
+set time_zone = default;
+show variables like 'time_zone';
+Variable_name	Value
+time_zone	SYSTEM
+set time_zone= '0';
+ERROR HY000: Unknown or incorrect time zone: '0'
+set time_zone= '0:0';
+ERROR HY000: Unknown or incorrect time zone: '0:0'
+set time_zone= '-20:00';
+ERROR HY000: Unknown or incorrect time zone: '-20:00'
+set time_zone= '+20:00';
+ERROR HY000: Unknown or incorrect time zone: '+20:00'
+set time_zone= 'Some/Unknown/Time/Zone';
+ERROR HY000: Unknown or incorrect time zone: 'Some/Unknown/Time/Zone'
+select convert_tz(now(),'UTC', 'Universal') = now();
+convert_tz(now(),'UTC', 'Universal') = now()
+1
+select convert_tz(now(),'utc', 'UTC') = now();
+convert_tz(now(),'utc', 'UTC') = now()
+1
+select convert_tz('1917-11-07 12:00:00', 'MET', 'UTC');
+convert_tz('1917-11-07 12:00:00', 'MET', 'UTC')
+1917-11-07 12:00:00
+select convert_tz('1970-01-01 01:00:00', 'MET', 'UTC');
+convert_tz('1970-01-01 01:00:00', 'MET', 'UTC')
+1970-01-01 01:00:00
+select convert_tz('1970-01-01 01:00:01', 'MET', 'UTC');
+convert_tz('1970-01-01 01:00:01', 'MET', 'UTC')
+1970-01-01 00:00:01
+select convert_tz('2003-03-01 00:00:00', 'MET', 'UTC');
+convert_tz('2003-03-01 00:00:00', 'MET', 'UTC')
+2003-02-28 23:00:00
+select convert_tz('2003-03-30 01:59:59', 'MET', 'UTC');
+convert_tz('2003-03-30 01:59:59', 'MET', 'UTC')
+2003-03-30 00:59:59
+select convert_tz('2003-03-30 02:30:00', 'MET', 'UTC');
+convert_tz('2003-03-30 02:30:00', 'MET', 'UTC')
+2003-03-30 01:00:00
+select convert_tz('2003-03-30 03:00:00', 'MET', 'UTC');
+convert_tz('2003-03-30 03:00:00', 'MET', 'UTC')
+2003-03-30 01:00:00
+select convert_tz('2003-05-01 00:00:00', 'MET', 'UTC');
+convert_tz('2003-05-01 00:00:00', 'MET', 'UTC')
+2003-04-30 22:00:00
+select convert_tz('2003-10-26 01:00:00', 'MET', 'UTC');
+convert_tz('2003-10-26 01:00:00', 'MET', 'UTC')
+2003-10-25 23:00:00
+select convert_tz('2003-10-26 02:00:00', 'MET', 'UTC');
+convert_tz('2003-10-26 02:00:00', 'MET', 'UTC')
+2003-10-26 00:00:00
+select convert_tz('2003-10-26 02:59:59', 'MET', 'UTC');
+convert_tz('2003-10-26 02:59:59', 'MET', 'UTC')
+2003-10-26 00:59:59
+select convert_tz('2003-10-26 04:00:00', 'MET', 'UTC');
+convert_tz('2003-10-26 04:00:00', 'MET', 'UTC')
+2003-10-26 03:00:00
+select convert_tz('2038-01-01 00:59:59', 'MET', 'UTC');
+convert_tz('2038-01-01 00:59:59', 'MET', 'UTC')
+2037-12-31 23:59:59
+select convert_tz('2038-01-01 01:00:00', 'MET', 'UTC');
+convert_tz('2038-01-01 01:00:00', 'MET', 'UTC')
+2038-01-01 01:00:00
+select convert_tz('2103-01-01 04:00:00', 'MET', 'UTC');
+convert_tz('2103-01-01 04:00:00', 'MET', 'UTC')
+2103-01-01 04:00:00
+create table t1 (tz varchar(3));
+insert into t1 (tz) values ('MET'), ('UTC');
+select tz, convert_tz('2003-12-31 00:00:00',tz,'UTC'), convert_tz('2003-12-31 00:00:00','UTC',tz) from t1 order by tz;
+tz	convert_tz('2003-12-31 00:00:00',tz,'UTC')	convert_tz('2003-12-31 00:00:00','UTC',tz)
+MET	2003-12-30 23:00:00	2003-12-31 01:00:00
+UTC	2003-12-31 00:00:00	2003-12-31 00:00:00
+drop table t1;
+select convert_tz('2003-12-31 04:00:00', NULL, 'UTC');
+convert_tz('2003-12-31 04:00:00', NULL, 'UTC')
+NULL
+select convert_tz('2003-12-31 04:00:00', 'SomeNotExistingTimeZone', 'UTC');
+convert_tz('2003-12-31 04:00:00', 'SomeNotExistingTimeZone', 'UTC')
+NULL
+select convert_tz('2003-12-31 04:00:00', 'MET', 'SomeNotExistingTimeZone');
+convert_tz('2003-12-31 04:00:00', 'MET', 'SomeNotExistingTimeZone')
+NULL
+select convert_tz('2003-12-31 04:00:00', 'MET', NULL);
+convert_tz('2003-12-31 04:00:00', 'MET', NULL)
+NULL
+select convert_tz( NULL, 'MET', 'UTC');
+convert_tz( NULL, 'MET', 'UTC')
+NULL