To get common articles and their quality assessments for two wikiprojects

SQL

SELECT
    p.page_title AS Article_Title,
    pa1.pa_class AS Quality_Class_Climate_Change,
    pa1.pa_importance AS Importance_Climate_Change,
    pa2.pa_class AS Quality_Class_Environment,
    pa2.pa_importance AS Importance_Environment
FROM
    page_assessments pa1
JOIN
    page_assessments pa2 ON pa1.pa_page_id = pa2.pa_page_id
JOIN
    page_assessments_projects pap1 ON pa1.pa_project_id = pap1.pap_project_id
JOIN
    page_assessments_projects pap2 ON pa2.pa_project_id = pap2.pap_project_id
JOIN
    page p ON pa1.pa_page_id = p.page_id
WHERE
    pap1.pap_project_title = 'Climate change'
    AND pap2.pap_project_title = 'Environment'
    AND pa1.pa_project_id != pa2.pa_project_id
GROUP BY
    p.page_title, pa1.pa_class, pa1.pa_importance, pa2.pa_class, pa2.pa_importance
ORDER BY
    p.page_title, pa1.pa_class, pa1.pa_importance, pa2.pa_class, pa2.pa_importance;

SQL

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