Hướng dẫn in file cad Informational, Transactional

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The role name of the user who will own the new database, or

CREATE DATABASE lusiadas;

3 to use the default (namely, the user executing the command). To create a database owned by another role, you must be able to

CREATE DATABASE lusiadas;

4 to that role.

CREATE DATABASE lusiadas;

5

The name of the template from which to create the new database, or

CREATE DATABASE lusiadas;

3 to use the default template (template1).

CREATE DATABASE lusiadas;

8

Character set encoding to use in the new database. Specify a string constant (e.g.,

CREATE DATABASE lusiadas;

9), or an integer encoding number, or

CREATE DATABASE lusiadas;

3 to use the default encoding (namely, the encoding of the template database). The character sets supported by the PostgreSQL server are described in . See below for additional restrictions.

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

1

Strategy to be used in creating the new database. If the

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

2 strategy is used, the database will be copied block by block and each block will be separately written to the write-ahead log. This is the most efficient strategy in cases where the template database is small, and therefore it is the default. The older

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

3 strategy is also available. This strategy writes a small record to the write-ahead log for each tablespace used by the target database. Each such record represents copying an entire directory to a new location at the filesystem level. While this does reduce the write-ahead log volume substantially, especially if the template database is large, it also forces the system to perform a checkpoint both before and after the creation of the new database. In some situations, this may have a noticeable negative impact on overall system performance.

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

4

Sets the default collation order and character classification in the new database. Collation affects the sort order applied to strings, e.g., in queries with

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

5, as well as the order used in indexes on text columns. Character classification affects the categorization of characters, e.g., lower, upper, and digit. Also sets the associated aspects of the operating system environment,

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

6 and

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

7. The default is the same setting as the template database. See and for details.

Can be overridden by setting , , or individually.

Tip

The other locale settings , , , and are not fixed per database and are not set by this command. If you want to make them the default for a specific database, you can use

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

8

Sets

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

6 in the database server's operating system environment. The default is the setting of if specified, otherwise the same setting as the template database. See below for additional restrictions.

If is

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

9

Sets

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

7 in the database server's operating system environment. The default is the setting of if specified, otherwise the same setting as the template database. See below for additional restrictions.

If is

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

Specifies the ICU locale (see ) for the database default collation order and character classification, overriding the setting . The must be ICU. The default is the setting of if specified; otherwise the same setting as the template database.

CREATE DATABASE music2

LOCALE 'sv_SE.iso885915'
ENCODING LATIN9
TEMPLATE template0;

Specifies additional collation rules to customize the behavior of the default collation of this database. This is supported for ICU only. See for details.

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

Specifies the provider to use for the default collation in this database. Possible values are

CREATE DATABASE music2

LOCALE 'sv_SE.iso885915'
ENCODING LATIN9
TEMPLATE template0;

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

`CREATE DATABASE`2

Specifies the collation version string to store with the database. Normally, this should be omitted, which will cause the version to be computed from the actual version of the database collation as provided by the operating system. This option is intended to be used by `CREATE DATABASE`3 for copying the version from an existing installation.

See also ALTER DATABASE for how to handle database collation version mismatches.

`CREATE DATABASE`4

The name of the tablespace that will be associated with the new database, or

CREATE DATABASE lusiadas;

3 to use the template database's tablespace. This tablespace will be the default tablespace used for objects created in this database. See CREATE TABLESPACE for more information.

`CREATE DATABASE`6

If false then no one can connect to this database. The default is true, allowing connections (except as restricted by other mechanisms, such as `CREATE DATABASE`7/`CREATE DATABASE`8).

`CREATE DATABASE`9

How many concurrent connections can be made to this database. -1 (the default) means no limit.

`CREATEDB`0

If true, then this database can be cloned by any user with CREATEDB privileges; if false (the default), then only superusers or the owner of the database can clone it.

`CREATEDB`2

The object identifier to be used for the new database. If this parameter is not specified, PostgreSQL will choose a suitable OID automatically. This parameter is primarily intended for internal use by pg_upgrade, and only pg_upgrade can specify a value less than 16384.

Optional parameters can be written in any order, not only the order illustrated above.

Notes

CREATE DATABASE cannot be executed inside a transaction block.

Errors along the line of “could not initialize database directory” are most likely related to insufficient permissions on the data directory, a full disk, or other file system problems.

Use `CREATEDB`4 to remove a database.

The program createdb is a wrapper program around this command, provided for convenience.

Database-level configuration parameters (set via `CREATEDB`5) and database-level permissions (set via `CREATE DATABASE`7) are not copied from the template database.

Although it is possible to copy a database other than template1 by specifying its name as the template, this is not (yet) intended as a general-purpose “CREATEDB`8” facility. The principal limitation is that no other sessions can be connected to the template database while it is being copied. `CREATE DATABASE will fail if any other connection exists when it starts; otherwise, new connections to the template database are locked out until CREATE DATABASE completes. See Section 23.3 for more information.

The character set encoding specified for the new database must be compatible with the chosen locale settings (

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

6 and

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

7). If the locale is template1`3 (or equivalently `template1`4), then all encodings are allowed, but for other locale settings there is only one encoding that will work properly. (On Windows, however, UTF-8 encoding can be used with any locale.) `CREATE DATABASE will allow superusers to specify `template1`6 encoding regardless of the locale settings, but this choice is deprecated and may result in misbehavior of character-string functions if data that is not encoding-compatible with the locale is stored in the database.

The encoding and locale settings must match those of the template database, except when `template1`7 is used as template. This is because other databases might contain data that does not match the specified encoding, or might contain indexes whose sort ordering is affected by

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

6 and

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

7. Copying such data would result in a database that is corrupt according to the new settings. `template1`7, however, is known to not contain any data or indexes that would be affected.

There is currently no option to use a database locale with nondeterministic comparisons (see TEMPLATE `name`1 for an explanation). If this is needed, then per-column collations would need to be used. The TEMPLATE `name`2 option is only enforced approximately; if two new sessions start at about the same time when just one connection “slot” remains for the database, it is possible that both will fail. Also, the limit is not enforced against superusers or background worker processes.

Examples

To create a new database:

CREATE DATABASE lusiadas;

To create a database TEMPLATE `name`3 owned by user TEMPLATE `name`4 with a default tablespace of TEMPLATE `name`5:

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

To create a database TEMPLATE `name`6 with a different locale:

CREATE DATABASE music

LOCALE 'sv_SE.utf8'
TEMPLATE template0;

To create a database TEMPLATE `name`9 with a different locale and a different character set encoding:

CREATE DATABASE music2

LOCALE 'sv_SE.iso885915'
ENCODING LATIN9
TEMPLATE template0;

Note that locale names are specific to the operating system, so that the above commands might not work in the same way everywhere.

Compatibility

There is no CREATE DATABASE statement in the SQL standard. Databases are equivalent to catalogs, whose creation is implementation-defined.