Enhancing data integrity: Alternatives to MySQL's ENUM in SQL Server 2005

This is the most common approach. You can create a separate table with the allowed values as the primary key. Then, create a foreign key relationship between your main table and the lookup table. This ensures data integrity and prevents invalid values from being entered.

Example:

-- Create the lookup table
CREATE TABLE Status (
  ID int PRIMARY KEY,
  StatusName nvarchar(50) UNIQUE
);

-- Insert allowed values
INSERT INTO Status (StatusName) VALUES ('Active'), ('Inactive'), ('Pending');

-- Create the main table with foreign key
CREATE TABLE Users (
  UserID int PRIMARY KEY,
  Username nvarchar(50),
  StatusID int FOREIGN KEY REFERENCES Status(ID)
);

CHECK constraint:

You can define a CHECK constraint on a string or integer column to restrict its values to a predefined list. However, this method doesn't offer the same level of data integrity as a separate lookup table and can be less efficient for complex validation rules.

CREATE TABLE Users (
  UserID int PRIMARY KEY,
  Username nvarchar(50),
  Status nvarchar(50) CHECK (Status IN ('Active', 'Inactive', 'Pending'))
);

Related Issues:

• Performance: CHECK constraints can be less efficient for complex validation rules compared to separate tables.
• Data integrity: Without a proper solution, invalid data might be entered into the column, leading to inconsistencies.

Choosing the right approach:

• For simpler scenarios with limited allowed values, a CHECK constraint might suffice.
• If data integrity is crucial, a lookup table is the preferred option.