Merge pull request #17 from olincollege/sv-silver

Added a silverdb folder and crosswalk code

src/night_light/silver_db/crosswalk.py

@@ -0,0 +1,25 @@
+from night_light.bronze_db.util import connect_to_duckdb
+
+def generate_silver_crosswalks() -> None: 
+    """
+    Creates crosswalk table for the silver database
+
+    Rewrites pervious verison of the table if it exists.
+    """
+    db_path = "silver.db"
+    conn = connect_to_duckdb(db_path)
+    conn.execute("ATTACH DATABASE 'bronze.db' AS bronze")
+
+    query = """
+    DROP TABLE IF EXISTS crosswalks;
+
+    CREATE TABLE crosswalks AS 
+    SELECT OBJECTID, Class_Loc, CrossType, geometry
+    FROM bronze.crosswalks;
+    """
+
+    conn.execute(query)
+    print("Silver table regenerated for crosswalks")
+
+if __name__ == "__main__":
+    generate_silver_crosswalks()