MySQL Query duplicates sum for left join

Question

I have 2 tables, Greeter_Detail and ZipCode_Details

I'm trying to SUM the total of People and Families from and Greeter_Detail and join them on ZipCodes, but I get duplicates. ZipCode_Details has city and county info. Can anyone help, I've been on this for hours. Seems like it should be straight forward. TIA!

 SELECT SUM(Families), SUM(People), Zipcode, ZipCode_Detail.Zipcode_D, ZipCode_Detail.City, ZipCode_Detail.County
 FROM Greeter_Detail
 
 LEFT JOIN ZipCode_Detail ON Greeter_Detail.Zipcode = ZipCode_Detail.Zipcode_D
 WHERE $dateRange
 GROUP BY Zipcode

• Rick James: Please provide SHOW CREATE TABLE.
• Rick James: It is unclear what you mean by "total of People". Can you provide a short set of data and the desired result?
• Full Array: Did you try to use SELECT DISTINCT OR use DISTINCT in one of the aggregate functions? I feel using the keyword DISTINCT is the key for your query and this question altogether. Let me know

Answer 1

COUNT(*) counts rows
COUNT(DISTINCT name) counts how many different `name` there are
SUM(cost > 1000) counts how many are expensive

Beware of what happens with NULL values; some counts include them; some don't.

If you need to gather two different counts from different tables, you may need subqueries for each count.

SELECT
 ( SELECT COUNT(*) ... ) AS foo_count
 ( SELECT COUNT(*) ... ) AS bar_count