Question

I’m creating a view where I pretty much replicate the data of the original user, but I also have an attribute in which I want to put the number of occurrences the user has in the downloads table.

CREATE VIEW customer_count_streams_vw(
sid_customer
systemuser_id
postcode
age
gender
num_streams) 
AS 
SELECT
user.sid_customer,
user.systemuser_id,
user.postcode,
user.age,
user.gender,
num_streams 
FROM md_customer 
INNER JOIN ods_streaming AS num_streams (
SELECT COUNT(ods_streaming.sid_customer) 
WHERE ods_streaming.sid_customer = md_customer.sid_customer)

What I want is to place the result of the part:

SELECT COUNT(ods_streaming.sid_customer) 
WHERE ods_streaming.sid_customer = md_customer.sid_customer

into the num_streams field.

Answer 1

Your query should be

SELECT
user.sid_customer,
user.systemuser_id,
user.postcode,
user.age,
user.gender,
num_streams 
FROM md_customer 
INNER JOIN 
( 
        SELECT sid_customer, COUNT(ods_streaming.sid_customer) num_streams 
        FROM ods_streaming group by sid_customer
) AS ods_streaming  
ON ods_streaming.sid_customer = md_customer.sid_customer

Above query will return rows for customers with row in md_customer and also a row in ods_streaming. If you want all customers and their count (including 0) then your query should be

SELECT
cust.sid_customer,
cust.systemuser_id,
cust.postcode,
cust.age,
cust.gender,
COUNT(strm.sid_customer) num_streams 
FROM 
   md_customer cust
LEFT OUTER JOIN ods_streaming  strm   
   ON cust.sid_customer = strm.sid_customer
group by 
cust.sid_customer,
cust.systemuser_id,
cust.postcode,
cust.age,
cust.gender