Create a unique table constraint to require that all non-null
values in specified columns be unique.
PrerequisitesÂ
Before you can create a unique constraint, be sure that the data server containing the tables is running, and you created and established a
connection to the data server.
- Expand the
Tables folder.
- Right-click the
table, and select
from the context menu.
The New Unique Constraint wizard opens.
- Specify properties
for the new unique constraint.
Field |
Description |
Unique constraint name |
Enter a name for the unique constraint in the text field.
|
Filter column by name pattern |
Optionally enter a filter expression for columns to be
displayed in the list of available columns. For example, * will list all
columns for the specified table.
|
Available columns |
This is a list of columns available for defining a unique
constraint. You can sort the list of columns by clicking on
Column Name above the list. Move a column
from the
Available columns list to the
Selected columns list in one of three
ways:
- Double-click the
column in the
Available columns list. This specifies
that the unique constraint is created in ascending order for this column.
- Highlight the
column, and click
ASC>>. This also specifies that
the unique constraint is created in ascending order for this column.
- Highlight the
column, and click
DESC>>. This specifies that the
unique constraint is created in descending order for this column.
|
Selected columns |
This is a list of columns selected as defining the unique
constraint. You can sort the list of columns by clicking on
Column Name above the list. You can also
reorder a list item by highlighting the column in the list and clicking
Up or
Down. To place a column back in the
Available columns list, highlight the
column and click
<<Remove.
|
Preview |
This field displays the DDL for creating the foreign key.
|
- Click
Next, and specify storage options for the
unique constraint.
Field |
Description |
Fill factor |
Choose the fill factor setting, which specifies how full
the data server makes each page when it creates a new unique constraint on
existing data. The deault is 0.
|
Maximum rows per page |
Specify the maximum number of rows on data pages and the
leaf-level pages of indexes. The default is 0.
|
Reserve page gap |
Specify the ratio of filled pages to empty pages to be left
during I/O allocation operations. For each specified number of pages, an empty
page is left for future expansion of the index. Valid values are 0 - 255. The
default is 0.
|
Create on segment |
Specify whether to create the unique constraint on a
default or system segment.
|
Clustered |
Specify whether or not to make the unique constraint
clustered.
|
- Click
Next, and specify save and execution
properties for the foreign key.
Field |
Description |
Generate script |
Select this option to generate DDL for the unique
constraint. |
Enter or select the parent folder |
Specify an existing project or create a new project in
which to save the DDL. |
File name |
Enter the name of the file in which to store the
DDL. |
Execute immediately |
Execute the DDL immediately. If you do not select this
option, you must complete execution of the DDL later to create the unique
constraint. |
Open in editor after creation |
Create the unique constraint, and then open it in the Table Schema Editor. |
- Click
Finish to create the unique constraint.
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