CREATE DOMAIN(7) SQL Commands CREATE DOMAIN(7)NAME
CREATE DOMAIN - define a new domain
SYNOPSIS
CREATE DOMAIN domainname [AS] data_type
[ DEFAULT default_expr ]
[ constraint [, ... ] ]
where constraint is:
[ CONSTRAINT constraint_name ]
{ NOT NULL | NULL }
PARAMETERS
domainname
The name (optionally schema-qualified) of a domain to be created.
data_type
The underlying data type of the domain. This may include array specifiers. Refer to the User's Guide for further information about
data types and arrays.
DEFAULT
The DEFAULT clause specifies a default value for columns of the domain data type. The value is any variable-free expression (but
subselects are not allowed). The data type of the default expression must match the data type of the domain.
The default expression will be used in any insert operation that does not specify a value for the column. If there is no default for
a domain, then the default is NULL.
Note: If a default value is specified for a particular column, it overrides any default associated with the domain. In turn, the
domain default overrides any default value associated with the underlying data type.
CONSTRAINT constraint_name
An optional name for a constraint. If not specified, the system generates a name.
NOT NULL
Values of this domain are not allowed to be NULL.
NULL Values of this domain are allowed to be NULL. This is the default.
This clause is only available for compatibility with non-standard SQL databases. Its use is discouraged in new applications.
OUTPUTS
CREATE DOMAIN
Message returned if the domain is successfully created.
DESCRIPTION
CREATE DOMAIN allows the user to register a new data domain with PostgreSQL for use in the current data base. The user who defines a domain
becomes its owner.
If a schema name is given (for example, CREATE DOMAIN myschema.mydomain ...) then the domain is created in the specified schema. Otherwise
it is created in the current schema (the one at the front of the search path; see CURRENT_SCHEMA()). The domain name must be unique among
the types and domains existing in its schema.
Domains are useful for abstracting common fields between tables into a single location for maintenance. An email address column may be used
in several tables, all with the same properties. Define a domain and use that rather than setting up each table's constraints individually.
EXAMPLES
This example creates the country_code data type and then uses the type in a table definition:
CREATE DOMAIN country_code char(2) NOT NULL;
CREATE TABLE countrylist (id INT4, country country_code);
COMPATIBILITY
SQL99 defines CREATE DOMAIN, but says that the only allowed constraint type is CHECK constraints. CHECK constraints for domains are not yet
supported by PostgreSQL.
SEE ALSO
DROP DOMAIN [drop_domain(7)], PostgreSQL Programmer's Guide
SQL - Language Statements 2002-11-22 CREATE DOMAIN(7)
Check Out this Related Man Page
CREATE SCHEMA(7) PostgreSQL 9.2.7 Documentation CREATE SCHEMA(7)NAME
CREATE_SCHEMA - define a new schema
SYNOPSIS
CREATE SCHEMA schema_name [ AUTHORIZATION user_name ] [ schema_element [ ... ] ]
CREATE SCHEMA AUTHORIZATION user_name [ schema_element [ ... ] ]
DESCRIPTION
CREATE SCHEMA enters a new schema into the current database. The schema name must be distinct from the name of any existing schema in the
current database.
A schema is essentially a namespace: it contains named objects (tables, data types, functions, and operators) whose names can duplicate
those of other objects existing in other schemas. Named objects are accessed either by "qualifying" their names with the schema name as a
prefix, or by setting a search path that includes the desired schema(s). A CREATE command specifying an unqualified object name creates the
object in the current schema (the one at the front of the search path, which can be determined with the function current_schema).
Optionally, CREATE SCHEMA can include subcommands to create objects within the new schema. The subcommands are treated essentially the same
as separate commands issued after creating the schema, except that if the AUTHORIZATION clause is used, all the created objects will be
owned by that user.
PARAMETERS
schema_name
The name of a schema to be created. If this is omitted, the user_name is used as the schema name. The name cannot begin with pg_, as
such names are reserved for system schemas.
user_name
The role name of the user who will own the new schema. If omitted, defaults to the user executing the command. To create a schema owned
by another role, you must be a direct or indirect member of that role, or be a superuser.
schema_element
An SQL statement defining an object to be created within the schema. Currently, only CREATE TABLE, CREATE VIEW, CREATE INDEX, CREATE
SEQUENCE, CREATE TRIGGER and GRANT are accepted as clauses within CREATE SCHEMA. Other kinds of objects may be created in separate
commands after the schema is created.
NOTES
To create a schema, the invoking user must have the CREATE privilege for the current database. (Of course, superusers bypass this check.)
EXAMPLES
Create a schema:
CREATE SCHEMA myschema;
Create a schema for user joe; the schema will also be named joe:
CREATE SCHEMA AUTHORIZATION joe;
Create a schema and create a table and view within it:
CREATE SCHEMA hollywood
CREATE TABLE films (title text, release date, awards text[])
CREATE VIEW winners AS
SELECT title, release FROM films WHERE awards IS NOT NULL;
Notice that the individual subcommands do not end with semicolons.
The following is an equivalent way of accomplishing the same result:
CREATE SCHEMA hollywood;
CREATE TABLE hollywood.films (title text, release date, awards text[]);
CREATE VIEW hollywood.winners AS
SELECT title, release FROM hollywood.films WHERE awards IS NOT NULL;
COMPATIBILITY
The SQL standard allows a DEFAULT CHARACTER SET clause in CREATE SCHEMA, as well as more subcommand types than are presently accepted by
PostgreSQL.
The SQL standard specifies that the subcommands in CREATE SCHEMA can appear in any order. The present PostgreSQL implementation does not
handle all cases of forward references in subcommands; it might sometimes be necessary to reorder the subcommands in order to avoid forward
references.
According to the SQL standard, the owner of a schema always owns all objects within it. PostgreSQL allows schemas to contain objects owned
by users other than the schema owner. This can happen only if the schema owner grants the CREATE privilege on his schema to someone else,
or a superuser chooses to create objects in it.
SEE ALSO
ALTER SCHEMA (ALTER_SCHEMA(7)), DROP SCHEMA (DROP_SCHEMA(7))
PostgreSQL 9.2.7 2014-02-17 CREATE SCHEMA(7)