<invoke name="query_sql"> <parameter name="sql">SELECT COUNT(*) AS n_rows, COUNT(DISTINCT Student_ID) AS distinct_ids, COUNT(Student_ID) AS ids_nonnull, COUNT(Academic_Performance_GPA) AS gpa_nonnull, COUNT(Perceived_Stress_Score) AS stress_nonnull, MIN(Daily_Usage_Hours) AS min_daily, MAX(Daily_Usage_Hours) AS max_daily, MIN(Weekend_Extra_Hours) AS min_wk, MAX(Weekend_Extra_Hours) AS max_wk, MIN(Sleep_Duration_Hours) AS min_sleep, MAX(Sleep_Duration_Hours) AS max_sleep, MIN(Age) AS min_age, MAX(Age) AS max_age, MIN(Sleep_Quality_Score) AS min_sq, MAX(Sleep_Quality_Score) AS max_sq, MIN(Mental_Health_Index) AS min_mh, MAX(Mental_Health_Index) AS max_mh, SUM(CASE WHEN Daily_Usage_Hours + Sleep_Duration_Hours > 20 THEN 1 ELSE 0 END) AS over_20h, SUM(CASE WHEN Academic_Level='High School' AND Age >= 19 THEN 1 ELSE 0 END) AS hs_age19plus, SUM(CASE WHEN Academic_Level='High School' THEN 1 ELSE 0 END) AS hs_total FROM raw.Social_media_impact_on_life</parameter> <parameter name="purpose">Verify data-quality claims: keys, nulls, ranges, time budget, age vs academic level</parameter> <parameter name="source">raw</parameter> </invoke>