mirror of
https://github.com/pgadmin-org/pgadmin4.git
synced 2024-12-22 15:13:42 -06:00
128 lines
5.1 KiB
ReStructuredText
128 lines
5.1 KiB
ReStructuredText
.. _domain_dialog:
|
|
|
|
**********************
|
|
`Domain Dialog`:index:
|
|
**********************
|
|
|
|
Use the *Domain* dialog to define a domain. A domain is a data type definition
|
|
that may constrain permissible values. Domains are useful when you are creating
|
|
multiple tables that contain comparable columns; you can create a domain that
|
|
defines constraints that are common to the columns and re-use the domain
|
|
definition when creating the columns, rather than individually defining each
|
|
set of constraints.
|
|
|
|
The *Domain* dialog organizes the development of a domain through the following
|
|
tabs: *General*, *Definition*, *Constraints*, and *Security*. The *SQL* tab
|
|
displays the SQL code generated by dialog selections.
|
|
|
|
.. image:: images/domain_general.png
|
|
:alt: Domain dialog general tab
|
|
:align: center
|
|
|
|
Use the fields on the *General* tab to identify a domain:
|
|
|
|
* Use the *Name* field to add a descriptive name for the domain. The name will
|
|
be displayed in the *pgAdmin* tree control.
|
|
* Use the drop-down listbox next to *Owner* to select a role that will own the
|
|
domain.
|
|
* Select the name of the schema in which the domain will reside from the
|
|
drop-down listbox in the *Schema* field.
|
|
* Store notes about the domain in the *Comment* field.
|
|
|
|
Click the *Definition* tab to continue.
|
|
|
|
.. image:: images/domain_definition.png
|
|
:alt: Domain dialog definition tab
|
|
:align: center
|
|
|
|
Use the fields in the *Definition* tab to describe the domain:
|
|
|
|
* Use the drop-down listbox next to *Base type* to specify a data type.
|
|
* Use the context-sensitive *Length* field to specify a numeric length for a
|
|
numeric type.
|
|
* Use the context-sensitive *Precision* field to specify the total count of
|
|
significant digits for a numeric type.
|
|
* Specify a default value for the domain data type in the *Default* field. The
|
|
data type of the default expression must match the data type of the domain. If
|
|
no default value is specified, then the default value is the null value.
|
|
* Move the *Not Null* switch to specify the values of this domain are prevented
|
|
from being null.
|
|
* Use the drop-down listbox next to *Collation* to apply a collation cast. If
|
|
no collation is specified, the underlying data type's default collation is
|
|
used. The underlying type must be collatable if COLLATE is specified.
|
|
|
|
Click the *Constraints* tab to continue.
|
|
|
|
.. image:: images/domain_constraints.png
|
|
:alt: Domain dialog constraints tab
|
|
:align: center
|
|
|
|
Use the fields in the *Constraints* tab to specify rules for the domain. Click
|
|
the *Add* icon (+) to set constraints:
|
|
|
|
* Use the *Name* field to specify a name for the constraint.
|
|
* Use the *Check* field to provide an expression for the constraint.
|
|
* Use the *Validate* checkbox to determine whether the constraint will be
|
|
validated. The default checkbox is checked and sets a validation requirement.
|
|
|
|
A CHECK clause specifies an integrity test which values of the domain must
|
|
satisfy. Each constraint must be an expression that produces a Boolean result.
|
|
Use the key word VALUE to refer to the value being tested. Expressions
|
|
evaluating to TRUE or UNKNOWN succeed. If the expression produces a FALSE
|
|
result, an error is reported and the value is not allowed to be converted to
|
|
the domain type. A CHECK expression cannot contain subqueries nor refer to
|
|
variables other than VALUE. If a domain has multiple CHECK constraints, they
|
|
will be tested in alphabetical order by name.
|
|
|
|
Click the *Add* icon (+) to set additional constraints; to discard a constraint,
|
|
click the trash icon to the left of the row and confirm deletion in the *Delete
|
|
Row* popup.
|
|
|
|
Click the *Security* tab to continue.
|
|
|
|
.. image:: images/domain_security.png
|
|
:alt: Domain dialog security tab
|
|
:align: center
|
|
|
|
Use the *Security Labels* panel to assign security labels. Click the *Add* icon
|
|
(+) to add a label:
|
|
|
|
* Specify a security label provider in the *Provider* field. The named provider
|
|
must be loaded and must consent to the proposed labeling operation.
|
|
* Specify a a security label in the *Security Label* field. The meaning of a
|
|
given label is at the discretion of the label provider. PostgreSQL places no
|
|
restrictions on whether or how a label provider must interpret security
|
|
labels; it merely provides a mechanism for storing them.
|
|
|
|
Click the *Add* icon (+) to specify each additional label; to discard a label,
|
|
click the trash icon to the left of the row and confirm deletion in the *Delete
|
|
Row* popup.
|
|
|
|
Click the *SQL* tab to continue.
|
|
|
|
Your entries in the *Domain* dialog generate a SQL command (see an example
|
|
below). Use the *SQL* tab for review; revisit or switch tabs to make any changes
|
|
to the SQL command.
|
|
|
|
Example
|
|
*******
|
|
|
|
The following is an example of the sql command generated by selections made in
|
|
the *Domain* dialog:
|
|
|
|
.. image:: images/domain_sql.png
|
|
:alt: Domain dialog sql tab
|
|
:align: center
|
|
|
|
The example shown demonstrates creating a domain named *postal_code* that
|
|
confirms that the value entered is in proper format.
|
|
|
|
* Click the *Info* button (i) to access online help.
|
|
* Click the *Save* button to save work.
|
|
* Click the *Close* button to exit without saving work.
|
|
* Click the *Reset* button to restore configuration parameters.
|
|
|
|
|
|
|
|
|