String Data Type

A string is a data type that holds text. Strings are enclosed in single quotes in SQL. The text inside can contain letters, numbers, spaces, punctuation, or special characters. A string could be as short as one character or as long as several megabytes of text. When you see values like 'Alice', 'alice@email.com', or 'San Francisco' in a database, those are strings. The single quotes tell the database "this is text, not a keyword or number." Before manipulating strings, it helps to understand how SQL represents and stores them. The following sections cover the basics of string syntax and type distinctions. String Literals in SQL You can use string literals directly in your queries by wrapping them in single quotes: The text 'Hello World' is a string literal. SQL treats it as a fixed text va

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.