As a SQL Server developer, I often come across unique requirements from clients that require a deeper understanding of their business needs. One such requirement is to validate that a column name is unique across the entire database. In this blog post, we will explore this requirement and discuss possible solutions.

Let’s start by understanding the scenario. The client wants to ensure that when a new column is added to the database, its name should not be repeated anywhere else in the database. The client’s reasoning behind this requirement is not explicitly stated, but it is important to understand the business need in order to provide an optimal solution.

One way to validate the uniqueness of a column name across the database is by using the sys.columns system view. Here are two options to achieve this:

Option 1: Check if Column Exists in Current Database

IF EXISTS (SELECT * FROM sys.columns WHERE Name = N'NameofColumn')
BEGIN
    SELECT 'Column Exists'
    -- add other logic
END
ELSE
BEGIN
    SELECT 'Column Does NOT Exist'
    -- add other logic
END

This option checks if the column name exists in any table within the current database. If it does, the code returns ‘Column Exists’, otherwise it returns ‘Column Does NOT Exist’.

Option 2: Check if Column Exists in Current Database in Specific Table

IF EXISTS (SELECT * FROM sys.columns WHERE Name = N'NameofColumn' AND OBJECT_ID = OBJECT_ID(N'tableName'))
BEGIN
    SELECT 'Column Exists'
    -- add other logic
END
ELSE
BEGIN
    SELECT 'Column Does NOT Exist'
    -- add other logic
END

This option is similar to the first one, but it also checks if the column exists in a specific table within the current database. It uses the OBJECT_ID function to specify the table name.

While these options provide a way to validate the uniqueness of a column name across the database, it is still unclear why the client has such a requirement. It is important to have a clear understanding of the business need in order to provide the most effective solution.

Have you ever faced a similar situation where you needed a unique column name across a database? If not, can you guess what could be the reason for this kind of requirement? Feel free to share your thoughts and experiences in the comments below.

Additional Reference: Query to Find Column From All Tables of Database