Adding Unique Constraints in SQL Server 2005
This guide demonstrates how to enforce uniqueness on columns within an existing SQL Server 2005 table. We'll cover both Transact-SQL (T-SQL) and the graphical Database Diagram methods.
Method 1: Using T-SQL
Employ the following T-SQL statement to add a unique constraint:
ALTER TABLE YourTableName ADD CONSTRAINT YourConstraintName UNIQUE NONCLUSTERED (YourColumnName)
Remember to replace:
-
YourTableName
with your table's name. -
YourConstraintName
with a descriptive name for the constraint. -
YourColumnName
with the column you wish to make unique.
Method 2: Utilizing the Database Diagram
- Right-click your table in the Database Diagram and choose "Indexes/Keys".
- Click "Add" to create a new index.
- In the Properties window, select the column(s) to be unique using the ellipsis button.
- Set the "Is Unique" property to "Yes".
- Provide a suitable name for the constraint.
These methods ensure data integrity by preventing duplicate entries in the specified column(s). Choose the approach that best suits your workflow.
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