vwedesam/SQL Re-Use alias named columns.md

## SQL Re-Use alias named columns.md

      
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              SQL Re-Use alias named columns.md
            
          
    SQL Re-Use alias named columns

USE named alias in SQL statement

You can't do it directly - you need to use something like a CTE (Common Table Expression)

E.g

SQL Calculate sum of two alias named columns

WITH SUMS AS 
(
   SELECT
      col1, col2, 
      SUM(col1) + SUM(col2) as Total,
      SUM(col1) + SUM(col2) as Total1 
   FROM
      table
   GROUP BY
      col1, col2
)
SELECT 
   col1, col2, 
   total, total1, 
   (total + total1) AS 'GrandTotal' 
FROM 
   SUMS