How can we apply multiple calculated column expressions in a single projection pass using selectExpr()?
selectExpr() accepts SQL expression strings to calculate mathematical operations, string conversions, and casts in a single Catalyst query plan node.
High-throughput batch transformations where chaining multiple withColumn calls would build deep lineage trees.
df_transformed = df.selectExpr("user_id", "upper(user_name) AS user_name", "price * quantity AS total_amount", "cast(created_at AS date) AS event_date")Practice typing production-grade PySpark code for Multiple Expression Pipeline.