Struggling with custom SQL query

问题

I have to make a query to:

show a view which shows the results of counting all the employee dedications per employee area, listed by the area names in alphabetical order.

$this->db->query('create temporary table temp as (select dedication.employee_employeeID, dedication ID, COUNT(area) AS TotalFrequency from dedication, employees where dedication.employee_employeeID = dedication group by dedication.employee_employeeID)');

However, doesn't seem to be working on my website?

here is my relationships:

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回答1:

I would recommend writing the query like this:

create temporary table temp as
    select c.industry, count(*) AS TotalFrequency
    from interest i JOIN
         customers c
         on i.staff_staffID = c.interestID
    group by c.industry;

This is just a guess. You haven't provided table layouts. The join conditions are quite strange (but wouldn't result in an error, just non-matches).

来源：https://stackoverflow.com/questions/55125970/struggling-with-custom-sql-query