Hussam w2 database #11
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yunchen4
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Sep 5, 2025
yunchen4
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yunchen4
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LGTM, just a suggestion for business requirement consideration.
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| await client.query(`SELECT RP.paper_title,COUNT(PA.author_id) FROM research_papers RP LEFT JOIN papers_authors PA ON RP.paper_id=PA.paper_id GROUP BY RP.paper_title`); | ||
| await client.query(`SELECT COUNT(PA.paper_id) AS total_papers_by_female FROM author A JOIN papers_authors PA ON A.author_id = PA.author_id WHERE A.gender = 'F';`); | ||
| await client.query(`SELECT A.university,AVG(A.h_index) AS avg_h_index FROM author A GROUP BY A.university;`); | ||
| await client.query(`SELECT A.university,COUNT(PA.paper_id) AS research_papers FROM author A JOIN papers_authors PA ON A.author_id=PA.author_id GROUP BY A.university`); | ||
| await client.query(`SELECT A.university,MIN(A.h_index) AS min_h_index,MAX(A.h_index) AS max_h_index FROM author A GROUP BY A.university`); |
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Your queries are correct. For query:
SELECT COUNT(PA.paper_id) AS total_papers_by_female FROM author A JOIN papers_authors PA ON A.author_id = PA.author_id WHERE A.gender = 'F';
If a paper has two different female authors, this paper will be counted twice. Depending on the business requirements, this might be what we want. If you don't want to count the same paper twice, you need to use DISTINCT keyword.
Similar thing happens for this query too:
SELECT A.university,COUNT(PA.paper_id) AS research_papers FROM author A JOIN papers_authors PA ON A.author_id=PA.author_id GROUP BY A.university
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