Add tested R query how-to and correct usage examples

README.md

@@ -52,6 +52,23 @@ FROM ussc.v_sentence_terms GROUP BY 1 ORDER BY 1;
 -- indicator (0 = no prison OR under one month); the view separates both.
 ```
 
+### R with DBI and duckdb
+
+Install the dependencies once with `install.packages(c("DBI", "duckdb"))`.
+
+```r
+library(DBI)
+con <- dbConnect(duckdb::duckdb())
+dbExecute(con, "INSTALL httpfs")
+dbExecute(con, "LOAD httpfs")
+dbExecute(con, "ATTACH 'https://huggingface.co/datasets/Nason/ussc-database/resolve/main/ussc.duckdb' AS ussc (READ_ONLY)")
+dbGetQuery(con, "SELECT fiscal_year FROM ussc.v_sentence_terms LIMIT 5")
+dbDisconnect(con, shutdown = TRUE)
+```
+
+DuckDB uses HTTP range requests; queries run on your machine and may need substantial memory or download data. A `LIMIT` does not guarantee a small scan.
+
+
 Or with the datapond packages: `pip install datapond` / `pak::pak("datapond-db/datapond-r")`.
 
 Build pipeline, the USSC codebook and caveats: https://github.com/ian-nason/ussc-database