Calling Stored Functions from SQL Expressions

You cannot call stored PL/SQL functions from a CHECK constraint clause of a CREATE or ALTER TABLE statement or use them to specify a default value for a column. These situations require an unchanging definition.

Note: Unlike functions, which are called as part of an expression, procedures are called as statements. Therefore, PL/SQL procedures are not directly callable from SQL statements. However, functions called from a PL/SQL statement or referenced in a SQL expression can call a PL/SQL procedure.

Syntax for SQL Calling a PL/SQL Function

Use the following syntax to reference a PL/SQL function from SQL:

[[schema.]package.]function_name[@dblink][(param_1...param_n)]

For example, to reference a function you created that is called My_func, in the My_ funcs_pkg package, in the Scott schema, that takes two numeric parameters, you could call the following:

SELECT Scott.My_funcs_pkg.My_func(10,20) FROM dual;

Naming Conventions

If only one of the optional schema or package names is given, then the first identifier can be either a schema name or a package name. For example, to determine whether Payroll in the reference Payroll.Tax_rate is a schema or package name, Oracle Database proceeds as follows:

■Oracle Database first checks for the Payroll package in the current schema.

■If the PAYROLL package is found in the current schema, then Oracle Database looks for a Tax_rate function in the Payroll package. If a Tax_rate function is not found in the Payroll package, then an error message is returned.

■If a Payroll package is not found, then Oracle Database looks for a schema named Payroll that contains a top-level Tax_rate function. If the Tax_rate

Using Procedures and Packages 7-51