Database function
A database function is a named routine stored or executed in a database that accepts inputs and computes a result, often a scalar or table-valued result.
Just Use Postgres!
A database function is a stored routine that accepts inputs, performs computation or data operations, and returns a value or result within the database.
- How it is used
- Deploys reusable data-coupled business logic and multistep operations for applications, microservices, and database-backed APIs.
- How deep it goes
- Defines SQL functions and demonstrates parameters, return tables, conditionals, updates, exceptions, and replacement, without deep administration guidance.
- Examples
- Uses product-price lookup, pending shopping carts, item addition, checkout totals, and database-backed message APIs as examples.
- What you can do after
- Build it from scratch using CREATE OR REPLACE FUNCTION, call it from SQL, inspect returned rows, and centralize multistep data workflows.
PostgreSQL Mistakes and How to Avoid Them
A database function is a named routine stored in the database that accepts inputs and produces a result or side effect.
- How it is used
- Uses stored routines to return values or perform database-side actions while emphasizing ownership and execution privileges.
- How deep it goes
- Explains execution privileges through a destructive scenario but stops short of function syntax or internal implementation.
- Examples
- Uses reset_schema(), count(), and data type conversion functions as examples of side effects, NULL handling, and migration compatibility.
- What you can do after
- Operate database functions more safely by reviewing ownership, execution rights, side effects, NULL behavior, and migration compatibility.
Read how PostgreSQL Mistakes and How to Avoid Them explains database function →
Learn SQL in a Month of Lunches
A database function is a named database routine or SQL operation that computes and returns a value, optionally from supplied arguments.
- How it is used
- Uses SQL functions to calculate, select, filter, transform, and inspect database values.
- How deep it goes
- Explains function purpose, argument syntax, practical categories, efficiency cautions, and RDBMS variation without covering implementation internals.
- Examples
- Demonstrates spreadsheet totals, aggregate calculations, and UPPER or LOWER applied to California customer names.
- What you can do after
- Apply it via SQL to calculate, extract, filter, combine, convert, or format values while recognizing portability and efficiency issues.
Read how Learn SQL in a Month of Lunches explains database function →
Related concepts
- SYSTEM$CLUSTERING_INFORMATIONincludes · SYSTEM$CLUSTERING_INFORMATION is a Snowflake system function that returns statistics describing how well a table is clustered for specified columns.
- coalesce functionincludes · The COALESCE function returns the first non-null value among its arguments, or null if all arguments are null.
- nowincludes · A now operation or keyword yields or derives a value representing the current date or time according to a relevant clock or system.
- timestampincludes · A timestamp is a value representing a specific point in time, typically associated with an event, observation, or data item.
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