Creating a Unique Constraint

Create a unique table constraint to require that all non-null values in specified columns be unique.

1. Expand the Tables folder.
2. Right-click the table, and select New > Unique Constraint .
3. Specify properties for the new unique constraint.

   Field	Description
   Unique Constraint Name	Enter a name for the unique constraint.
   Filter Column by Name Pattern	(Optional) Enter a filter expression for columns to be displayed in the list of available columns. For example, * lists all columns for the specified table.
   Available Columns	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, which specifies that the unique constraint is created in ascending order for this column. Highlight the column, and click ASC>>, which specifies that the unique constraint is created in ascending order for this column. Highlight the column, and click DESC>>, which specifies that the unique constraint is created in descending order for this column.
   Selected Columns	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	DDL for creating the foreign key.

4. 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 default 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 to make the unique constraint clustered.

5. Click Next, and specify save and execution properties for the foreign key.

   Field	Description
   Generate Script	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.

6. Click Finish to create the unique constraint.

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