Skip to main content
DatabricksPySparkSnowflakeApache Airflow
Code Keys/PySpark Academy/Module 09/Lesson 69
PYSPARK • LESSON 69

First Non-Null Selection with coalesce()

How do we select the first available phone number from mobile, home phone, or a fallback 'N/A' literal?

Intermediate⏱ 2 Minutes⭐ 360 XP
🤔 THE QUESTION

How do we select the first available phone number from mobile, home phone, or a fallback 'N/A' literal?

💡 WHAT IS IT?

coalesce() evaluates Column arguments from left to right and returns the first non-null value.

🎯 WHAT IS IT USED FOR?

Customer contact resolution, priority channel fallback, and merging multi-source address fields.

💻 EXAMPLE
from pyspark.sql.functions import col, coalesce, lit

df = df.withColumn(
    "contact_phone",
    coalesce(col("mobile"), col("home_phone"), lit("N/A"))
)

🎯 Mission Objectives

Practice typing production-grade PySpark code for First Non-Null Selection with coalesce().

  • ✓ Import coalesce and lit
  • ✓ Evaluate contact phone priority order
  • ✓ Assign resolved phone with fallback
🚀 Start Mission
← Prev (Dropping Corrupted Rows with dropna())Next Lesson (Conditional NULL Handling with when()) →