How can I use SQL computed columns?

To use computed column in sql server, Go to your database, right click on tables, select the “New Table” option. Create all columns that you require and to mark any column as computed, select that column and go to column Properties window and write your formula for the computed column. A computed column is a virtual column that is not physically stored in the table, unless the column is marked PERSISTED. A computed column expression can use data from other columns to calculate a value for the column to which it belongs. As per your question,I think you are asking is - how do I use the result of one calculated column in another? Well, if you want to actually add that column to the table you could just inline the calculation within your new column - this would work but requires more maintenance and is probably not an ideal solution (this also works in a SELECT statement but can increase maintenance overhead):

CREATE TABLE T ( A INT NOT NULL , X INT NOT NULL , (CASE A WHEN NULL THEN 0 ELSE 1 END) AS B , (CASE A WHEN NULL THEN 0 ELSE 1 END) * X AS C ); This can become messy and can be painful to maintain if the calculations are complicated. You can however define your base calculations on the table and then put a view over the top which can then use your calculated columns: CREATE VIEW V AS SELECT A, B, B * X AS C FROM T; This is my recommendation due to how really simple it is to maintain because the logic is isolated. The calculation of C never needs to know how B is calculated, it just uses the value that is generated. If you don't like that, then your other option is to define the logic within the query against the table itself and then perform the calculation on that. There are a few ways to do this, here are a couple of the ones I prefer:COMMON TABLE EXPRESSIONS -- CTE Method WITH results AS ( SELECT A , (CASE A WHEN NULL THEN 0 ELSE 1 END) AS B , X -- don't forget to include the other columns you need! FROM MyTable ) SELECT A, B, B * X AS C FROM results; SUBQUERIES -- SubQuery SELECT A, B, B * X AS C FROM (SELECT A , (CASE A WHEN NULL THEN 0 ELSE 1 END) AS B , X -- don't forget to include the other columns you need! FROM MyTable) AS results; TABLE VARIABLE

  -- Total overkill, but can be done (could also use a temp table instead) DECLARE @results TABLE ( A INT NOT NULL, B INT NOT NULL, X INT NOT NULL ); INSERT @results SELECT A , (CASE A WHEN NULL THEN 0 ELSE 1 END) AS B , X -- don't forget to include the other columns you need! FROM MyTable; SELECT A, B, B * X AS C FROM @results;