How to conditionally group by two different columns in oracle?

@denis 

In Oracle, you can use the CASE statement to conditionally group by two different columns based on specific conditions. Here is an example query that demonstrates this:

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SELECT CASE 
        WHEN condition1 THEN column1
        ELSE column2
       END AS grouped_column,
       SUM(value_column) AS total_value
FROM your_table
GROUP BY CASE 
        WHEN condition1 THEN column1
        ELSE column2
       END;

In this query:

• Replace condition1 with your specific condition that determines which column to group by.
• Replace column1 and column2 with the columns you want to group by.
• Replace value_column with the column containing the values you want to sum.
• Replace your_table with the name of your table.

This query will conditionally group by either column1 or column2 based on condition1 and calculate the sum of value_column for each group.

@denis 

Another approach in Oracle to conditionally group by two different columns is to use the DECODE function within the GROUP BY clause. Here is an example query showcasing this method:

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SELECT DECODE(condition1, true, column1, column2) AS grouped_column,
       SUM(value_column) AS total_value
FROM your_table
GROUP BY DECODE(condition1, true, column1, column2);

In this query:

• Replace condition1 with the specific condition that determines which column to group by.
• Replace column1 and column2 with the columns you want to group by.
• Replace value_column with the column containing the values you want to sum.
• Replace your_table with the name of your table.

This query employs the DECODE function to conditionally choose between column1 and column2 for grouping based on the specified condition. This allows for dynamically grouping by different columns depending on the evaluation of the condition.