Assignment w2 HANNA MELNYK

[hanna-melnyk]

No description provided.

[rafaelhdr]

Exercises are going very well. Easy to read and review.

But exercise 4 is failing. It is something very small that is raising an error. Could you investigate the issue, please?

When we run it, we get this:

node exercise_4.js
An error occurred: TypeError: Cannot read properties of undefined (reading 'query')
    at file:///.../connection_query.js:20:20
    at new Promise (<anonymous>)
    at useDatabase (file:///home/rafaelhdr/hyf/hanna/Week2/connection_query.js:15:12)
    at exerciseFour (file:///home/rafaelhdr/hyf/hanna/Week2/exercise_4.js:148:15)
    at file:///home/rafaelhdr/hyf/hanna/Week2/exercise_4.js:162:5
    at ModuleJob.run (node:internal/modules/esm/module_job:217:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:316:24)
    at async loadESM (node:internal/process/esm_loader:34:7)
    at async handleMainPromise (node:internal/modules/run_main:66:12)

[hanna-melnyk]

Exercises are going very well. Easy to read and review.

But exercise 4 is failing. It is something very small that is raising an error. Could you investigate the issue, please?

When we run it, we get this:

node exercise_4.js
An error occurred: TypeError: Cannot read properties of undefined (reading 'query')
    at file:///.../connection_query.js:20:20
    at new Promise (<anonymous>)
    at useDatabase (file:///home/rafaelhdr/hyf/hanna/Week2/connection_query.js:15:12)
    at exerciseFour (file:///home/rafaelhdr/hyf/hanna/Week2/exercise_4.js:148:15)
    at file:///home/rafaelhdr/hyf/hanna/Week2/exercise_4.js:162:5
    at ModuleJob.run (node:internal/modules/esm/module_job:217:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:316:24)
    at async loadESM (node:internal/process/esm_loader:34:7)
    at async handleMainPromise (node:internal/modules/run_main:66:12)

Rafael, thanks for the feedback!
I've changed the exercise_4.js file. Hope it works now.

[rafaelhdr]

So quick. Thanks for checking.

But the issue is not on the require.main

Try to compare how you are calling the SQL methods (try checking how you are calling the useDatabase in exercise 4 with the exercise 3). It is really something very small.

[rafaelhdr]

It is really good. Congratulations. I just wanted to share a suggestion, but the query provided works good.

[rafaelhdr]

I would recommend to do this query like this:

            SELECT 
                COUNT(author_papers.paper_id) AS total_papers
            FROM 
                author_papers
            LEFT JOIN 
                authors ON author_papers.author_id = authors.author_id 
            WHERE authors.gender = 'Female' 

If we have a index for gender, the performance would be better because we don't need to go through all rows.

But your answer is correct. I would just recommend use WHERE if possible.