CONCAT()

Concepts covered: sqlConcat

Basic Concatenation The most common use case is combining first and last names into a full name: The query takes first_name, adds a space ' ', then adds last_name. The space is a literal string argument. Without it, you would get 'AliceChen' instead of 'Alice Chen'. Building Complex Strings Advanced Usage Multiple Arguments Handling Empty Values Best Practices When to Use CONCAT() At scale, even simple string operations can become performance bottlenecks.

About This Interactive Section

This section is part of the String Functions: Beginner lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

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DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.