About User Defined Functions
User defined functions enable you to invoke externally available functions from PL/SQL or SQL code within your database.
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Oracle Cloud Infrastructure Functions: Oracle Cloud Infrastructure Functions are fully managed, multi-tenant, highly scalable, on-demand, Functions-as-a-Service platform. Oracle Cloud Infrastructure Functions are built on enterprise-grade Oracle Cloud Infrastructure and powered by the Fn Project open-source engine. Use Oracle Cloud Infrastructure Functions also referred to as OCI Functions, to focus on developing code to meet the business requirements. See Overview of Functions for more information. 
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AWS Lambda: AWS Lambda is a serverless, event-driven compute service that lets you run code for virtually any application or backend service without provisioning or managing servers. See AWS Lambda for more information. 
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Azure Function: Azure Function is a serverless compute service that enables users to run event-triggered code without provisioning or managing infrastructure. See Azure Functions overview and Create your first function in the Azure portal for more information. 
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External Procedures: External procedures are functions written in a third-generation language (C, for example) and callable from within PL/SQL or SQL as if they were a PL/SQL routine or function. See What Is an External Procedure? for more information. 
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Google Cloud Run Function: Google Cloud Run function is a serverless compute service that enables user to run event-triggered code without having to provision or manage infrastructure. See Google Cloud Run functions for more information. 
Parent topic: Invoke User Defined Functions