Query required to compress multiple records

Question

I have a table containing customer name and module as follows
Customer        Module_id         Company_Name
AAA                   9                       ABC
AAA                  13                      ABC
AAA                  21                      ABC
AAA                    5                      ABC
BB                     6                       XYZ
BB                     7                       XYZ
BB                     21                     XYZ
CCC                  13                      EFG
CCC                    6                      EFG
CCC                    7                     EFG
DD                     13                     UVW
DD                       9                    UVWI want to retrieve customer and company name which have
module id as 9 or 13 but NOT 21
The criteria I used is module_id in (9,13) and module_id <> 21
However the output is:
CCC EFG
DD UVW
DD UVW
The output I want is:
CCC EFG,
DD UVW (Only once)
Can any body provide the query?

Answer 1

Sounds like you need to put DISTINCT in your select or use a group by.
I.e
select distinct customer, company
from your tables
where your table join
module_id in (9,13) and module_id <> 21
or
select customer, company
from your tables
where your table join
module_id in (9,13) and module_id <> 21
group by customer, company