ApsaraDB RDS for SQL Server instances ship with a default collation (Chinese_PRC_CI_AS) and time zone (China Standard Time). If your application stores multilingual data or handles timestamps across multiple time zones, you can change these settings to match your requirements.
Before you change either setting, consider whether you are building a new application or migrating an existing one:
New application: Use UTC as the time zone. UTC eliminates ambiguity when storing and comparing timestamps across regions.
Migrating from on-premises SQL Server: Match the collation and time zone of your source instance to avoid unexpected query behavior after migration. To check your source instance's collation, run
SELECT SERVERPROPERTY(N'Collation')on the on-premises instance.
Both operations restart the instance and cause downtime. Plan changes during a maintenance window.
Background information
ApsaraDB RDS for SQL Server instances include the following system databases: master, msdb, tempdb, and model.
Limitations
Shared instance type family: the time zone cannot be changed. For supported instance types, see Instance families.
Serverless ApsaraDB RDS instances: neither collation nor time zone can be changed. See Serverless ApsaraDB RDS for SQL Server instances.
Change the character set collation
Changing the collation restarts the instance and makes it unavailable for 2–10 minutes.
The collation change option is only available when no user databases exist on the instance. If the option is not visible in the console, delete all user databases first. After deleting databases, confirm that neither the primary instance nor its secondary instance contains user databases before proceeding, as the deletion task may still be pending on the secondary.
Understanding collation suffixes
Collation names encode their sort behavior in suffixes. The default Chinese_PRC_CI_AS is case-insensitive and accent-sensitive. The table below decodes the common suffix combinations so you can choose the right collation from the console dropdown.
| Suffix | Meaning |
|---|---|
_CI | Case-insensitive (WHERE name = 'Alice' matches alice) |
_CS | Case-sensitive (WHERE name = 'Alice' does not match alice) |
_AI | Accent-insensitive |
_AS | Accent-sensitive |
_BIN | Binary sort order (byte-level comparison) |
For self-managed databases on the same instance, change the collation at the database level without restarting the instance:
ALTER DATABASE <database_name> COLLATE <collation_name>;Steps
Log on to the ApsaraDB RDS console. In the top navigation bar, select the region where the instance resides. Find the instance and click its ID.
In the left-side navigation pane, click Databases.
On the Databases page, click Modify Character Set Collation Rule.
In the dialog box, select the target collation in the Character Set Collation Rule field and click OK. The instance restarts immediately. It is unavailable for 2–10 minutes.
After the instance is available again, go to the Basic Information page to confirm the new collation. To verify with T-SQL, run:
SELECT SERVERPROPERTY('Collation');
Change the time zone
Changing the time zone restarts the instance. Downtime depends on the edition:
| Edition | Downtime |
|---|---|
| High-availability Edition or Cluster Edition | Up to 1 minute |
| Basic Edition | Up to 5 minutes |
What the time zone setting affects
The instance time zone governs the following SQL Server behaviors:
GETDATE(),SYSDATETIME(), and other local-time functionsSQL Server Agent job schedules
CLR code that reads the system time
It does not affect:
Data stored with explicit UTC offsets (e.g.,
datetimeoffsetcolumns)Application-layer time handling
Some time zones observe daylight saving time (DST). When DST begins or ends, the clock shifts forward or back by one hour. The DST flag column in the time zones and UTC offsets table identifies which time zones observe DST.
Steps
Log on to the ApsaraDB RDS console. In the top navigation bar, select the region where the instance resides. Find the instance and click its ID.
In the left-side navigation pane, click Databases.
On the Databases page, click Change Time Zone.
In the dialog box, select the target time zone in the Time Zone field and click OK. For available time zones and their UTC offsets, see Time zones and UTC offsets. The instance restarts immediately.
In the confirmation dialog box, click OK.
After the instance is available again, go to the Basic Information page to confirm the new time zone. To verify with T-SQL, run:
SELECT CURRENT_TIMEZONE();
Time zones and UTC offsets
Daylight saving time (DST) is a period during which clocks are set forward by one hour from standard time. The start and end dates vary by country and region. Time zones with a DST flag of DST+1 hour observe this adjustment.
| Time zone | UTC offset | DST flag | Description |
|---|---|---|---|
| Afghanistan Standard Time | (UTC+04:30) | None | Kabul |
| Alaskan Standard Time | (UTC-09:00) | DST+1 hour | Alaska |
| Aleutian Standard Time | (UTC-10:00) | DST+1 hour | Aleutian Islands |
| Altai Standard Time | (UTC+07:00) | None | Barnaul, Gorno-Altaysk |
| Arab Standard Time | (UTC+03:00) | None | Kuwait, Riyadh |
| Arabian Standard Time | (UTC+04:00) | None | Abu Dhabi, Muscat |
| Arabic Standard Time | (UTC+03:00) | None | Baghdad |
| Argentina Standard Time | (UTC-03:00) | None | City of Buenos Aires |
| Astrakhan Standard Time | (UTC+04:00) | None | Astrakhan, Ulyanovsk |
| Atlantic Standard Time | (UTC-04:00) | DST+1 hour | Atlantic Time (Canada) |
| AUS Central Standard Time | (UTC+09:30) | None | Darwin |
| AUS Eastern Standard Time | (UTC+10:00) | DST+1 hour | Canberra, Melbourne, Sydney |
| Aus Central W. Standard Time | (UTC+08:45) | None | Eucla |
| Azerbaijan Standard Time | (UTC+04:00) | None | Baku |
| Azores Standard Time | (UTC-01:00) | DST+1 hour | Azores |
| Bahia Standard Time | (UTC-03:00) | DST+1 hour | Salvador |
| Bangladesh Standard Time | (UTC+06:00) | None | Dhaka |
| Belarus Standard Time | (UTC+03:00) | None | Minsk |
| Bougainville Standard Time | (UTC+11:00) | None | Bougainville Island |
| Canada Central Standard Time | (UTC-06:00) | None | Saskatchewan |
| Cape Verde Standard Time | (UTC-01:00) | None | Cabo Verde Is. |
| Caucasus Standard Time | (UTC+04:00) | None | Yerevan |
| Cen. Australia Standard Time | (UTC+09:30) | None | Adelaide |
| Central America Standard Time | (UTC-06:00) | None | Central America |
| Central Asia Standard Time | (UTC+06:00) | None | Astana |
| Central Brazilian Standard Time | (UTC-04:00) | None | Cuiaba |
| Central Europe Standard Time | (UTC+01:00) | None | Belgrade, Bratislava, Budapest, Ljubljana, Prague |
| Central European Standard Time | (UTC+01:00) | DST+1 hour | Sarajevo, Skopje, Warsaw, Zagreb |
| Central Pacific Standard Time | (UTC+11:00) | None | Solomon Islands, New Caledonia |
| Central Standard Time | (UTC-06:00) | DST+1 hour | Central Time (US and Canada) |
| Central Standard Time (Mexico) | (UTC-06:00) | None | Guadalajara, Mexico City, Monterrey |
| Chatham Islands Standard Time | (UTC+12:45) | DST+1 hour | Chatham Islands |
| China Standard Time | (UTC+08:00) | None | Beijing, Chongqing, Hong Kong, Urumqi |
| Dateline Standard Time | (UTC-12:00) | None | International Date Line West |
| E. Africa Standard Time | (UTC+03:00) | None | Nairobi |
| E. Australia Standard Time | (UTC+10:00) | DST+1 hour | Brisbane |
| E. Europe Standard Time | (UTC+02:00) | DST+1 hour | Chisinau |
| E. South America Standard Time | (UTC-03:00) | None | Brasilia |
| Easter Island Standard Time | (UTC-06:00) | DST+1 hour | Easter Island |
| Eastern Standard Time | (UTC-05:00) | DST+1 hour | Eastern Time (US and Canada) |
| Eastern Standard Time (Mexico) | (UTC-05:00) | None | Chetumal |
| Egypt Standard Time | (UTC+02:00) | DST+1 hour | Cairo |
| Ekaterinburg Standard Time | (UTC+05:00) | None | Ekaterinburg |
| Fiji Standard Time | (UTC+12:00) | None | Fiji |
| FLE Standard Time | (UTC+02:00) | DST+1 hour | Helsinki, Kyiv, Riga, Sofia, Tallinn, Vilnius |
| Georgian Standard Time | (UTC+04:00) | None | Tbilisi |
| GMT Standard Time | (UTC) | None | Dublin, Edinburgh, Lisbon, London |
| Greenland Standard Time | (UTC-03:00) | DST+1 hour | Greenland |
| Greenwich Standard Time | (UTC) | None | Monrovia, Reykjavik |
| GTB Standard Time | (UTC+02:00) | DST+1 hour | Athens, Bucharest |
| Haiti Standard Time | (UTC-05:00) | DST+1 hour | Haiti |
| Hawaiian Standard Time | (UTC-10:00) | None | Hawaii |
| India Standard Time | (UTC+05:30) | None | Chennai, Kolkata, Mumbai, New Delhi |
| Israel Standard Time | (UTC+02:00) | DST+1 hour | Jerusalem |
| Jordan Standard Time | (UTC+02:00) | None | Amman |
| Kaliningrad Standard Time | (UTC+02:00) | None | Kaliningrad |
| Kamchatka Standard Time | (UTC+12:00) | DST+1 hour | Petropavlovsk-Kamchatsky - Old |
| Korea Standard Time | (UTC+09:00) | None | Seoul |
| Libya Standard Time | (UTC+02:00) | DST+1 hour | Tripoli |
| Line Islands Standard Time | (UTC+14:00) | None | Kiritimati Island |
| Lord Howe Standard Time | (UTC+10:30) | DST+1 hour | Lord Howe Island |
| Magadan Standard Time | (UTC+11:00) | None | Magadan |
| Magallanes Standard Time | (UTC-03:00) | DST+1 hour | Punta Arenas |
| Marquesas Standard Time | (UTC-09:30) | None | Marquesas Islands |
| Mauritius Standard Time | (UTC+04:00) | None | Port Louis |
| Mid-Atlantic Standard Time | (UTC-02:00) | None | Mid-Atlantic - Old |
| Middle East Standard Time | (UTC+02:00) | None | Beirut |
| Montevideo Standard Time | (UTC-03:00) | None | Montevideo |
| Morocco Standard Time | (UTC+01:00) | DST+1 hour | Casablanca |
| Mountain Standard Time | (UTC-07:00) | DST+1 hour | Mountain Time (US and Canada) |
| Mountain Standard Time (Mexico) | (UTC-07:00) | None | Chihuahua, La Paz, Mazatlan |
| Myanmar Standard Time | (UTC+06:30) | None | Yangon (Rangoon) |
| N. Central Asia Standard Time | (UTC+07:00) | None | Novosibirsk |
| Namibia Standard Time | (UTC+02:00) | DST+1 hour | Windhoek |
| Nepal Standard Time | (UTC+05:45) | None | Kathmandu |
| New Zealand Standard Time | (UTC+12:00) | DST+1 hour | Auckland, Wellington |
| Newfoundland Standard Time | (UTC-03:30) | DST+1 hour | Newfoundland |
| Norfolk Standard Time | (UTC+11:00) | DST+1 hour | Norfolk Island |
| North Asia East Standard Time | (UTC+08:00) | DST+1 hour | Irkutsk |
| North Asia Standard Time | (UTC+07:00) | None | Krasnoyarsk |
| Omsk Standard Time | (UTC+06:00) | None | Omsk |
| Pacific SA Standard Time | (UTC-03:00) | None | Santiago |
| Pacific Standard Time | (UTC-08:00) | DST+1 hour | Pacific Time (US and Canada) |
| Pacific Standard Time (Mexico) | (UTC-08:00) | None | Baja California |
| Pakistan Standard Time | (UTC+05:00) | None | Islamabad, Karachi |
| Paraguay Standard Time | (UTC-04:00) | DST+1 hour | Asuncion |
| Romance Standard Time | (UTC+01:00) | DST+1 hour | Brussels, Copenhagen, Madrid, Paris |
| Russian Standard Time | (UTC+03:00) | None | Moscow, St. Petersburg, Volgograd |
| SA Eastern Standard Time | (UTC-03:00) | None | Cayenne, Fortaleza |
| SA Pacific Standard Time | (UTC-05:00) | None | Bogota, Lima, Quito, Rio Branco |
| SA Western Standard Time | (UTC-04:00) | None | Georgetown, La Paz, Manaus, San Juan |
| Saint Pierre Standard Time | (UTC-03:00) | DST+1 hour | Saint Pierre and Miquelon |
| Sakhalin Standard Time | (UTC+11:00) | None | Sakhalin |
| Samoa Standard Time | (UTC+13:00) | DST+1 hour | Samoa |
| Sao Tome Standard Time | (UTC+01:00) | None | Sao Tome |
| Saratov Standard Time | (UTC+04:00) | None | Saratov |
| SE Asia Standard Time | (UTC+07:00) | None | Bangkok, Hanoi, Jakarta |
| Singapore Standard Time | (UTC+08:00) | None | Kuala Lumpur, Singapore |
| South Africa Standard Time | (UTC+02:00) | None | Harare, Pretoria |
| Sri Lanka Standard Time | (UTC+05:30) | None | Sri Jayawardenepura |
| Sudan Standard Time | (UTC+02:00) | None | Khartoum |
| Taipei Standard Time | (UTC+08:00) | None | Taipei |
| Tasmania Standard Time | (UTC+10:00) | DST+1 hour | Hobart |
| Tocantins Standard Time | (UTC-03:00) | DST+1 hour | Araguaina |
| Tokyo Standard Time | (UTC+09:00) | None | Osaka, Sapporo, Tokyo |
| Tomsk Standard Time | (UTC+07:00) | None | Tomsk |
| Tonga Standard Time | (UTC+13:00) | None | Nuku'alofa |
| Transbaikal Standard Time | (UTC+09:00) | None | Chita |
| Turkey Standard Time | (UTC+03:00) | None | Istanbul |
| Turks And Caicos Standard Time | (UTC-05:00) | DST+1 hour | Turks and Caicos |
| Ulaanbaatar Standard Time | (UTC+08:00) | None | Ulaanbaatar |
| US Eastern Standard Time | (UTC-05:00) | DST+1 hour | Indiana (East) |
| US Mountain Standard Time | (UTC-07:00) | None | Arizona |
| UTC | UTC | None | Coordinated Universal Time |
| UTC-02 | (UTC-02:00) | None | Coordinated Universal Time-02 |
| UTC-08 | (UTC-08:00) | None | Coordinated Universal Time-08 |
| UTC-09 | (UTC-09:00) | None | Coordinated Universal Time-09 |
| UTC-11 | (UTC-11:00) | None | Coordinated Universal Time-11 |
| UTC+12 | (UTC+12:00) | None | Coordinated Universal Time+12 |
| UTC+13 | (UTC+13:00) | None | Coordinated Universal Time+13 |
| Venezuela Standard Time | (UTC-04:00) | None | Caracas |
| Vladivostok Standard Time | (UTC+10:00) | DST+1 hour | Vladivostok |
| Volgograd Standard Time | (UTC+04:00) | None | Volgograd |
| W. Australia Standard Time | (UTC+08:00) | None | Perth |
| W. Central Africa Standard Time | (UTC+01:00) | None | West Central Africa |
| W. Europe Standard Time | (UTC+01:00) | DST+1 hour | Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna |
| W. Mongolia Standard Time | (UTC+07:00) | DST+1 hour | Hovd |
| West Asia Standard Time | (UTC+05:00) | None | Ashgabat, Tashkent |
| West Bank Standard Time | (UTC+02:00) | DST+1 hour | Gaza, Hebron |
| West Pacific Standard Time | (UTC+10:00) | None | Guam, Port Moresby |
| Yakutsk Standard Time | (UTC+09:00) | None | Yakutsk |
API reference
Use the following API operations to query or change the collation and time zone programmatically:
DescribeCollationTimeZones — list available collations and time zones
ModifyCollationTimeZone — change collation or time zone