有关SQL查询的问题

Question

Given a relation R with n columns. Use sql to returns the tuples having the maximum number of occurrences of the values. I have no idea how to do query horizontally?

Answer 1

SELECT MAX(t.*) FROM mytable t

or

SELECT DISTINCT a, b, c FROM mytable

or

SELECT DISTINCT * FROM mytable

it depends on which SQL implementation you are referring to, and generally more information about the query. but the above examples should get you started so you can google some terms.

Answer 2

I'm not sure what you mean by querying horizontally. Is it one relation with multiple key columns linking the two tables? Sounds like you might just need to group by those columns and order by count(*) descending...