EASY WAY TO CREATE A VIEW FROM THE TABLE IN SQL

I came across a challenge that required creating a view from a very complex table with 30+ columns. The goal was to create a view almost mirroring the original table, excluding just one specific column. Creating views in SQL Server can be a powerful way to abstract complex queries, however, when dealing with tables containing a large number of columns, the classic method of manually listing each column that you want to include in the View can be very time-consuming and prone to errors.

Consider this example: Let’s say you have a table named ‘YourTable’, and you want to create a view excluding the column ‘ExcludedColumn’. The SQL statement would look like this:

CREATE VIEW YourView
AS 
SELECT
Column1,
Column2,
Column3,
Column4,
…, 
ColumnN
FROM YourTable;

The SELECT statement would contain all the columns that we need for the View, and this approach works, but manually listing every column in the SELECT statement takes time, especially if you have many columns and want to exclude just one. Unfortunately, there is no built-in function in SQL Server to auto-generate the View script from the table automatically. A more convenient and efficient alternative is to generate the column list programmatically using dynamic SQL. Here’s an example of how to do it:

Example: Dynamic SQL for View Creation:

DECLARE @columns NVARCHAR(MAX);

SELECT @columns = STRING_AGG(column_name, ', ')
FROM information_schema.columns
WHERE table_name = 'YourTable' AND column_name != 'ExcludedColumn';

DECLARE @sql NVARCHAR(MAX);

SET @sql = 'CREATE VIEW YourView AS SELECT ' + @columns + ' FROM YourTable;';
PRINT @sql;

All you need to change is replace ‘YourTable’ with the actual name of your table, and ‘ExcludedColumn’ with the actual name of the column you want to exclude. This adjustment ensures the code aligns with your specific table and column preferences. Once you’ve made these changes, execute the code, and the View will be generated accordingly. In this example, the STRING_AGG function is used to dynamically retrieve all column names from the table. The dynamic SQL statement is then constructed, incorporating these columns into the SELECT statement.

The STRING_AGG function that has been used in this example was introduced in SQL Server 2017, so if you are using an earlier version, you won’t be able to use this function. If you are unsure about the version of SQL Server you are using, you can check it by running the following query:

SELECT @@VERSION;

For older versions of SQL Server, we can use alternative methods to concatenate strings like the COALESCE function in the example below.

DECLARE @columns NVARCHAR(MAX);

SELECT @columns = COALESCE(@columns + ', ', '') + column_name
FROM information_schema.columns
WHERE table_name = 'YourTable' AND column_name != 'ExcludedColumn';

DECLARE @sql NVARCHAR(MAX);

SET @sql = 'CREATE VIEW YourView AS SELECT ' + @columns + ' FROM YourTable;';
PRINT @sql;

Both scripts will dynamically generate the column list excluding the specified column and then create the view using dynamic SQL. In scenarios like this, using dynamic SQL is a more efficient alternative. It significantly speeds up the view creation process, saving time and effort. Moreover, it allows the query to adapt seamlessly to changes in the underlying table structure. If columns in the table are added or removed, the dynamic version adjusts automatically, ensuring the view remains up-to-date. One notable benefit is that developers can focus on the query logic without being overwhelmed by an extensive list of column names.

Dynamic SQL comes up as a valuable tool when dealing with the challenge of creating views for tables with a large number of columns, it is practical, efficient and time-saving — everything we need for a smoother development process.

Thank you for exploring this efficient approach with me. If you have any thoughts or questions, feel free to share them. Happy coding!