Sql 查询用于选择多列中的不同值

Question

I have a table say which has two columns zip code and customer code . Suppose there are multiple customer code with same zipcode . I need to fetch the above two columns such that one column contains unique zipcode and the second column contains the number of unique customer codes for the corresponding zip code.

The problem here is there can be more than one unique customer for a single zip code(Kind of like a single customer might have gone to a shop in same zip code more than once but I need to treat them as one)

How can I do it in SQLite . I did the following SQL query and I get only single zip code

select distinct(C.pin_code),count(distinct(C.customer_code)) from customers as C inner join Sales as S on S.customer_code=C.customer_code

The output is

I don't know how this comes about.If you need any more info please let me know in comments.

Answer 1

You are describing group by :

select zip_code, count(distinct customer_code)
from t
group by zip_code;

I have no idea what your query has to do with the question. The question is explicitly about a single table with two columns.

Note: You probably don't need count(distinct) -- unless there are multiple rows for a single customer in a single zip code.