SELECT DISTINCT HAVING Count unique conditions

Question

I\'ve searched for an answer on this but can\'t find quite how to get this distinct recordset based on a condition. I have a table with the following sample data:

Answer 1

You could write your first query as this:

Select Type, Color, Count(Distinct Location) As UniqueLocations
From Table
Group By Type, Color
Having Count(Distinct Location) > 1

(if you're using MySQL you could use the alias UniqueLocations in your having clause, but on many other systems the aliases are not yet available as the having clause is evaluated before the select clause, in this case you have to repeat the count on both clauses).

And for the second one, there are many different ways to write that, this could be one:

Select Distinct Type, Color, Location
From Table
Where
  Exists (
    Select
      *
    From
      Table Table_1
    Where
      Table_1.Type = Table.Type
      and Table_1.Color = Table.Color
    Group By
      Type, Color
    Having
      Count(Distinct Location) > 1
  )