Unique Constraint Dialog v9
Use the Unique constraint
dialog to define a unique constraint for a specified table. Unique constraints ensure that the data contained in a column, or a group of columns, is unique among all the rows in the table.
The Unique constraint
dialog organizes the development of a unique 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 unique constraint:
- Use the
Name
field to add a descriptive name for the unique constraint. The name will be displayed in theBrowser
tree control.
Click the Definition
tab to continue.
Use the fields in the Definition
tab to define the unique constraint:
- Click inside the
Columns
field and select one or more column names from the drop-down listbox. To delete a selection, click thex
to the left of the column name. The unique constraint should be different from the primary key constraint defined for the same table; the selected column(s) for the constraints must be distinct. - Use
Include columns
field to specify columns forINCLUDE
clause of the constraint. This option is available in Postgres 11 and later. - Select the name of the tablespace in which the unique constraint will reside from the drop-down listbox in the
Tablespace
field. - Select the name of an index from the drop-down listbox in the
Index
field. This field is optional. Adding a unique constraint will automatically create a unique B-tree index on the column or group of columns listed in the constraint, and will force the column(s) to be marked NOT NULL. - Use the
Fill Factor
field to specify a fill factor for the table and index. The fill factor for a table is a percentage between 10 and 100. 100 (complete packing) is the default. - Move the
Deferrable?
switch to theYes
position to specify the timing of the constraint is deferrable and can be postponed until the end of the statement. The default isNo
. - If enabled, move the
Deferred?
switch to theYes
position to specify the timing of the constraint is deferred to the end of the statement. The default isNo
.
Click the SQL
tab to continue.
Your entries in the Unique constraint
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 user selections in the Unique constraint
dialog:
The example shown demonstrates creating a unique constraint named name_con
on the name
column of the distributors
table.
- Click the
Info
button (i) to access online help. View context-sensitive help in theTabbed browser
, where a new tab displays the PostgreSQL core documentation. - Click the
Save
button to save work. - Click the
Cancel
button to exit without saving work. - Click the
Reset
button to restore configuration parameters.