CALL

Purpose

Use the CALL statement to execute a routine (a standalone procedure or function, or a procedure or function defined within a type or package) from within SQL.

Prerequisites

You must have EXECUTE privilege on the standalone routine or on the type or package in which the routine is defined.

Syntax

call::=

Text description of call

Semantics

schema

Specify the schema in which the standalone routine (or the package or type containing the routine) resides. If you do not specify schema, then Oracle assumes the routine is in your own schema.

type or package

Specify the type or package in which the routine is defined.

function | procedure | method

Specify the name of the function or procedure being called, or a synonym that translates to a function or procedure.

When you call a type's member function or procedure, if the first argument (SELF) is a null IN OUT argument, then Oracle returns an error. If SELF is a null IN argument, then Oracle returns null. In both cases, the function or procedure is not invoked.

Restriction on Functions

If the routine is a function, then the INTO clause is mandatory.

@dblink

In a distributed database system, specify the name of the database containing the standalone routine (or the package or function containing the routine). If you omit dblink, then Oracle looks in your local database.

object_access_expression

If you have an expression of an object type, such as a type constructor or a bind variable, you can use the object_access_expression syntax to call a routine defined within the type.

The syntax permitted in this context is a subset of object access expressions (see "Object Access Expressions"). Used within the CALL statement, you can invoke only methods (not attributes), and object_expr must be a literal (not a column name or other nonliteral expression). Therefore, the syntax allowed is:

expression.method

where expression is the literal expression of the object type and method is a member method of the object type.

argument

Specify one or more arguments to the routine, if the routine takes arguments.

Restrictions on Arguments to the Routine

• An argument cannot be a pseudocolumn or either of the object reference functions VALUE or REF.
• Any argument that is an IN OUT or OUT argument of the routine must correspond to a host variable expression.

INTO :host_variable

The INTO clause applies only to calls to functions. Specify which host variable will store the return value of the function.

:indicator_variable

Specify the value or condition of the host variable.

Example

Calling a Procedure: Example

The following statement uses the remove_dept procedure (created in "Creating a Package Body: Example") to remove the Entertainment department (created in "Inserting Sequence Values: Example"):

CALL remove_dept(162); 

Calling a Procedure Using an Expression of an Object Type: Example

The following examples show how call a procedure by using an expression of an object type in the CALL statement. The example uses the warehouse_typ object type in the order entry sample schema OE:

ALTER TYPE warehouse_typ
      ADD MEMBER FUNCTION ret_name
      RETURN VARCHAR2
      CASCADE;

CREATE OR REPLACE TYPE BODY warehouse_typ
      AS MEMBER FUNCTION ret_name
      RETURN VARCHAR2
      IS
         BEGIN
            RETURN self.warehouse_name;
         END;
      END;
/
VARIABLE x VARCHAR2(25);

CALL warehouse_typ(456, 'Warehouse 456', 2236).ret_name()
   INTO :x;

PRINT x;
X
--------------------------------
Warehouse 456

The next example shows how to use an external function to achieve the same thing:

CREATE OR REPLACE FUNCTION ret_warehouse_typ(x warehouse_typ) 
  RETURN warehouse_typ
  IS
    BEGIN
      RETURN x;
    END;
/
CALL ret_warehouse_typ(warehouse_typ(234, 'Warehouse 234',
   2235)).ret_name()
   INTO :x;

PRINT x;

X
--------------------------------
Warehouse 234