Unique Keys Wizard (SQL Server)
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Unique keys can enforce logical keys that are not chosen as the primary key. In other words, you can use a unique key to ensure no duplicate values are entered in specific columns that are not a part of the primary key. Although you can only attach one primary key to a table, you can attach multiple unique keys. Also, you can use unique keys on columns that allow null values.
To create a new unique key using a wizard:
- Open a creation wizard for a unique key. For details, see Opening an Object Wizard.
- Use the following topics as a guide to setting properties and performing tasks as you pass through the wizard panels:
- Properties panel - Unique Keys (SQL Server) - Properties.
- Columns panel - Unique Keys (SQL Server) - Columns.
- DDL View panel - for details, see Previewing the DDL Generated to Create the New Object.
- Finally, use the Execute button to create the object.
Unique Keys (SQL Server) - Properties
When creating or editing a unique key, this tab/panel lets you work with the following settings:
| Setting | Description |
|---|---|
|
Table Owner and Table Name |
Choose the owner and name of the table in which the unique key is being created. |
|
Name |
Provide a name of the unique key being created. |
|
Build Online |
Enabling this feature specifies that the ONLINE=ON clause is used when creating this object and can subsequently be used when rebuilding or dropping this object. |
|
Max degree of parallelism |
Lets you specify a MAXDOP index operation value, limiting the number of processors used in parallel plan execution. |
|
Clustered |
Enable or disable clustering. With this check box enabled, subsequent rebuild and drop operations offer an online option. |
|
File Group |
If you do not specify a filegroup, Microsoft SQL Server creates the unique key in the default filegroup. |
|
Fill Factor |
This specifies how full each index page that’s storing data should be. The fill factor is a percentage value between 0 and 100. |
Unique Keys (SQL Server) - Columns
From the Column dropdown, select a column for the primary key and specify a Sort option. To add more columns, click the New button and then follow the steps in the last instruction. Use the Delete button to drop columns.
