笔记
有人告诉我如何将单列存储的多行值存储到单个变量中，并代表该变量一次单击就将返回的值存储在表中如何使用pl/sql实现这种场景。
像这样的查询返回一列多行，我想把它存储到一些var中，并在单击过程中插入所有值。它将生成错误的错误图像

DECLARE
    l_respondent_id   VARCHAR(100);
BEGIN
    FOR c IN (
        SELECT
            s.gr_number
        FROM
            student s
            LEFT JOIN class_time ct ON ct.class_id = s.class_id
                                       AND instr(s.class_time, ct.class_time) > 0
        WHERE
            upper(TRIM(ct.class_id)) = upper(TRIM(:app_user))
            AND s.gr_number IS NOT NULL
            AND is_active_flg = 'Y'
    ) LOOP
        l_respondent_id := c.gr_number;
        BEGIN
            SELECT
                s.gr_number
            INTO l_respondent_id
            FROM
                student s
                LEFT JOIN class_time ct ON ct.class_id = s.class_id
                                           AND instr(s.class_time, ct.class_time) > 0
            WHERE
                upper(TRIM(ct.class_id)) = upper(TRIM(:app_user))
                AND s.gr_number IS NOT NULL
                AND is_active_flg = 'Y'
                AND s.gr_number = c.gr_number;

        EXCEPTION
            WHEN no_data_found THEN
                l_respondent_id := NULL;
        END;

        IF l_respondent_id IS NULL THEN
            INSERT INTO student_class_attend ( gr_number ) VALUES ( c.gr_number ) RETURNING gr_number INTO l_respondent_id;

        END IF;

    END LOOP;
END;