How Can I Use a Calculated Column in Subsequent Calculations Within the Same Query?

Using a Calculated Column to Calculate Another Column in the Same View

Consider a situation where you have a table with columns ColumnA, ColumnB, and ColumnC, and in a view, you have included a calculated column calccolumn1 as ColumnA ColumnB.

To utilize calccolumn1 in a subsequent calculation within the same query, there are two approaches:

1. Nested Query:

Employ a nested query to compute calccolumn1 first, then include this calculation in the outer query for further calculations:

Select
  ColumnA,
  ColumnB,
  calccolumn1,
  calccolumn1 / ColumnC as calccolumn2
From (
  Select
    ColumnA,
    ColumnB,
    ColumnC,
    ColumnA + ColumnB As calccolumn1
  from t42
);

2. Repeating Calculation:

An alternative method is to repeat the calculation explicitly, especially if it's not computationally intensive:

Select
  ColumnA,
  ColumnB,
  ColumnA + ColumnB As calccolumn1,
  (ColumnA + ColumnB) / ColumnC As calccolumn2
from t42;

By following either approach, you can leverage a calculated column to perform additional calculations within the same query, enabling you to derive new insights from your data efficiently.

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