Basic Concepts# Introduction DataFrame Expressions Dataframe Creating a Dataframe Executing our DataFrame and Viewing Data When should I materialize my DataFrame? Schemas and Types Running Computations Expressions Expressions Creating Expressions Referring to a column in a DataFrame Refer to a column with a certain name Literals Numeric Expressions String Expressions URL Expressions JSON Expressions Logical Expressions Comparisons If Else Pattern Reading/Writing Reading Data From Files From Data Catalogs From File Paths From Memory From Databases Writing Data