To view a function in SQL, particularly when working with database systems such as PostgreSQL or Microsoft SQL Server, you can leverage system catalog views or built-in functions. For PostgreSQL, you would typically use the `pg_proc` system catalog, which holds the definitions of all functions defined in the database. For example, to fetch details about a specific function, you can execute a query like `SELECT proname, prosrc FROM pg_proc WHERE proname = ‘your_function_name’;`. This will provide you with the function’s name and its source code. In SQL Server, you can use the built-in `sys.sql_modules` view in conjunction with `sys.objects`, querying them as follows: `SELECT o.name, m.definition FROM sys.sql_modules m JOIN sys.objects o ON m.object_id = o.object_id WHERE o.type_desc = ‘SQL_SCALAR_FUNCTION’ AND o.name = ‘your_function_name’;`. This will return the function’s definition which includes its SQL code.

While these examples demonstrate how to directly view a function’s code, it’s often beneficial to understand the broader theoretical backdrop of function creation and execution in SQL. Keep in mind that functions can have various properties such as deterministic behavior, input parameters, and return types. Therefore, besides merely looking at the source, checking for dependencies (using `pg_depend` in PostgreSQL or `sys.sql_expression_dependencies` in SQL Server) can provide insights into how the function interacts with other database objects and its role within the overall schema. Additionally, tools such as database management interfaces (like pgAdmin for PostgreSQL or SQL Server Management Studio) can simplify the process by allowing you to navigate through database objects visually, enabling easier exploration and management of functions without extensive SQL knowledge.