How to Efficiently Establish Data Uniqueness in SQL Server 2005?

Ensuring Data Integrity in SQL Server 2005: Implementing Unique Constraints

The Challenge:

Maintaining database integrity requires preventing duplicate entries. Unique constraints are crucial for this, guaranteeing that a column or set of columns within a table holds only distinct values. This document outlines efficient methods for achieving this in SQL Server 2005.

SQL Solution:

The Transact-SQL (T-SQL) command to add a unique constraint to an existing table is:

ALTER TABLE <tablename> ADD CONSTRAINT
            <constraintname> UNIQUE NONCLUSTERED
    (
                <columnname>
    )

Visual Approach (Database Diagram):

Alternatively, use the database diagram for a visual workflow:

1. Right-click the table and select "Indexes/Keys."
2. Click "Add" to create a new index.
3. In the "Properties" window:
   • Select the relevant columns (use the ellipsis button).
   • Check "Is Unique."
   • Provide a descriptive constraint name.

These methods empower database administrators and developers to effectively eliminate data redundancy, strengthen data integrity, and guarantee the reliability of query outputs.

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