initial code

sql/01_safe_data_overview.sql

@@ -0,0 +1,53 @@
+-- Aggregate-only starter queries. Do not select VIN, plate, email, session,
+-- upload-log, or raw JSON fields into a public-facing application.
+BEGIN TRANSACTION READ ONLY;
+
+SELECT
+    count(*) AS registration_records,
+    min(registration_date) AS earliest_registration,
+    max(registration_date) AS latest_registration
+FROM data.dmv_tax;
+
+SELECT
+    extract(year FROM registration_date)::integer AS registration_year,
+    count(*) AS records
+FROM data.dmv_tax
+GROUP BY 1
+ORDER BY 1;
+
+SELECT
+    upper(trim(county)) AS county,
+    count(*) AS records
+FROM data.dmv_tax
+GROUP BY 1
+ORDER BY 2 DESC;
+
+SELECT
+    upper(replace(trim(fuel_type), '-', ' ')) AS canonical_fuel_type,
+    count(*) AS records
+FROM data.dmv_tax_vehicle
+GROUP BY 1
+ORDER BY 2 DESC;
+
+SELECT
+    count(*) AS inspection_records,
+    min(test_start) AS earliest_test,
+    max(test_start) AS latest_test
+FROM data.inspection_search;
+
+SELECT
+    extract(year FROM test_start)::integer AS test_year,
+    count(*) AS records
+FROM data.inspection_search
+GROUP BY 1
+ORDER BY 1;
+
+SELECT
+    lower(trim(county)) AS county_source,
+    coalesce(nullif(upper(trim(overall_result)), ''), '<BLANK/NULL>') AS result,
+    count(*) AS records
+FROM data.inspection_search
+GROUP BY 1, 2
+ORDER BY 1, 3 DESC;
+
+ROLLBACK;