Get frequent data for each column of a table

Question

What is the best way to get the most frequent data in each column of a table.
we have around 25 tables and each table has around 20 columns , so rather than writing group by for each column of table , is there any easy way to find this?
example we have table
Column A       Column B         Column C
Apple             Monday             Red
orange            Tuesday            Green
Apple              Monday            Red
Lemon            Wednesday       Green
Apple               Thursday         Red
in this table, column A's frequnt data is Apple , column B's frequent data is Monday , Column C's frequnt data is Red
Apple 3          Monday 2                  Red 3
Orange 2        Tuesday 1                 Green 2
Lemon 1          Wednesday 1         
                      Thursday 1
Group by kind of query will give this result, but with 20 tables each having 20 - 30 columns if we need similar kind of result ..  is there any way to get this data.

Answer 1

Hi,
GROUP BY (using aggregate functions) is the best way to do what you described.
PIVOT and UNPIVOT are probably what you'd want in this case.  The phrase "GROUP BY" may not actually appear in your code, but you'll essentially be doing a GROUP BY.
Analytic functions (rather than aggregate functions) can do the job, too, but they'll be less efficient.  Analytic functions get you results about the groups, without losing each row's identify, but in this case, losing each row's identity is eactly what you want to do.  You only want 'Apple' to appear 1 time, not 3 times.
The fact that you need to do the same query on 20 different tables suggests that there's something wrong with your table design.  Wouldn't it be better to have 1 big table, with a new column that has 20 unique values instead?
I hope this answers your question.
If not, please post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) from all tables involved, so that the people who want to help you can re-create the problem and test their ideas.
Also post the results you want from that data, and an explanation of how you get those results from that data, with specific examples.
Simplify the problem as much as possible.  For example, instead of posting a problem with 20 tables, each having 25 columns, post a similar problem involving, say, 2 tables, each with 3 columns.
Always say which version of Oracle you're using (for example, 11.2.0.2.0).
See the forum FAQ: https://forums.oracle.com/message/9362002