了解Oracle函数中的“批量收集”

你所能做的就是用一个选择 MAX 或 COUNT

AS
..
..

v_retval VARCHAR2(10);


SELECT MAX(CASE 
            WHEN category = 'FOO'
                AND id = my_id 
                THEN 'Y'
            ELSE 'N'
            END) INTO v_retval
FROM my_table;
RETURN v_retval;

这取决于字符串“y”>“n”的事实。您也可以使用 COUNT(CASE .. 还有另一个案子 where count > 1 THEN 'Y'

p_id p_category

BULK COLLECT

LIMIT

Kaushik's solution

id ROWNUM = 1 WHERE

FUNCTION foo(p_id NUMBER, p_category VARCHAR) RETURN CHAR IS
n NUMBER;
BEGIN
    SELECT id INTO n FROM table WHERE id = p_id AND p_category = 'FOO';
    RETURN 'Y';
EXCEPTION WHEN OTHERS THEN
    RETURN 'N';
END;