Add: Cast TIMESTAMP_NTZ to BIGINT in Spark

Closes #240

Author: github-actions[bot]

_questions/data-engineering-zoomcamp/module-6/063_c2c5634e36_cast-timestamp-ntz-to-bigint-spark.md

@@ -0,0 +1,13 @@
+---
+id: c2c5634e36
+question: Why does casting TIMESTAMP_NTZ to BIGINT fail in Spark, and how can I convert
+  it to a numeric value?
+sort_order: 63
+---
+
+TIMESTAMP_NTZ cannot be cast directly to numeric types like BIGINT in Spark. To convert to a numeric representation (epoch seconds), use the to_unix_timestamp function.
+
+```sql
+SELECT to_unix_timestamp(tpep_pickup_datetime)
+FROM yellow_2025_11
+```