假设我有一个 PL/SQL 存储过程,如下所示:
PROCEDURE do_something(foo VARCHAR2 DEFAULT NULL) IS
BEGIN
/* Do something */
END;
现在,假设do_something
有两种不同的调用方式:
/* Scenario 1: The 'foo' parameter defaults to NULL */
do_something();
/* Scenario 2: The 'foo' parameter is explicitly set to NULL */
do_something(foo => NULL)
如何定义do_something
过程以确定调用它的场景?
编辑:澄清我对此过程的意图:
FUNCTION find_customer(name VARCHAR2 DEFAULT NULL, number VARCHAR2 DEFAULT NULL) RETURN NUMBER IS
BEGIN
/* Query the "customer" table using only those parameters provided */
END;
以下是此过程与所需的关联 SQL 子句的示例用法:
/* SELECT * FROM customer WHERE customer.name = 'Sam' */
find_customer(name => 'Sam')
/* SELECT * FROM customer WHERE customer.name = 'Sam' AND customer.number = '1588Z' */
find_customer(name => 'Sam', number => '1588Z')
/* SELECT * FROM customer WHERE customer.name = 'Sam' AND customer.number IS NULL */
find_customer(name => 'Sam', number => NULL)
/* SELECT * FROM customer WHERE customer.name IS NULL */
find_customer(name => NULL)
/* SELECT * FROM customer WHERE customer.name IS NULL AND customer.number IS NULL */
find_customer(name => NULL, number => NULL)