Ask a Question
Report a Bug
This page in other versions:
This document in other formats:
Use the Domain Constraints dialog to create or modify a domain constraint. A
domain constraint confirms that the values provided for a domain meet a defined
criteria. The Domain Constraints dialog implements options of the ALTER DOMAIN
The Domain Constraints dialog organizes the development of a domain constraint
through the following dialog tabs: General and Definition. The SQL tab
displays the SQL code generated by dialog selections.
Use the fields in the General tab to identify the domain constraint:
Use the Name field to add a descriptive name for the constraint. The name
will be displayed in the pgAdmin tree control.
Store notes about the constraint in the Comment field.
Click the Definition tab to continue.
Use the fields in the Definition tab to define the domain constraint:
Use the Check field to provide a CHECK expression. A CHECK expression
specifies a constraint that the domain must satisfy. A constraint must produce
a Boolean result; include the key word VALUE to refer to the value being
tested. Only those expressions that evaluate to TRUE or UNKNOWN will succeed.
A CHECK expression cannot contain subqueries or refer to variables other than
VALUE. If a domain has multiple CHECK constraints, they will be tested in
Move the Validate? switch to the No position to mark the constraint NOT
VALID. If the constraint is marked NOT VALID, the constraint will not be
applied to existing column data. The default value is Yes.
Click the SQL tab to continue.
Your entries in the Domain Constraints 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.
The following is an example of the sql command generated by user selections in
the Domain Constraints dialog:
The example shown demonstrates creating a domain constraint on the domain
timesheets named weekday. It constrains a value to equal Friday.
Click the Info button (i) to access online help.
Click the Save button to save work.
Click the Cancel button to exit without saving work.
Click the Reset button to restore configuration parameters.