Group by and having clause

[pramod talekar]

I have the below product table :
A      1232  PC A      1233  PC A      1276  Printer A      1298  Laptop A      1401  Printer A      1408  Printer A      1752  Laptop B      1121   PC B      1750  Laptop C      1321  Laptop D      1288  Printer D      1433  Printer E      1260  PC E      1434  Printer E      2112  PC E      2113  PC
I want to find out the makers who produce only one product type and more than one model.
The answer is
Maker Type D        Printer
So far, I have written this query:
Select maker, type from product   group by type, maker having count(model) > 1
It gives the below result:
maker type A     Laptop A     PC A     Printer D     Printer E     PC
My question is how to write condition to get result for 1 type only ? as writing having count(type)=1 removes maker D which is required.

[Stephan van Hulst]

Let's take a step back and first create a result table that shows how many types each maker has. That means you should group by just the maker, and not by the maker and the type.

This is the result I want, build a query to achieve it:

maker	number of types
A	3
B	2
C	1
D	1
E	2

[Tushar Goel]

may be like :

select maker from <table-name> group by maker having count(maker) = 1

[Stephan van Hulst]

Are you guessing, Tushar, or are you testing your query against an actual DBMS? You'll find that your query does not return the result I asked Pramod to give me.

Your query likely gives me the following result:

A

B

C

D

E