为什么我的显式游标仅从 PL/SQL 中的数据库中提取特定行？

Question

我是 PL/SQL 的新手，我正在尝试使用显式游标遍历我的数据库 FLEX_PANEL_INSPECTIONS。我想使用显式游标依次从数据库中获取每一行，并根据行中给定 'panel' 的随机生成 'status'，在 if 中为面板分配一个新的状态值/else 语句。面板的状态是随机的但布尔值 - 它是 1 或 0。但是，当我查看 DBMS 输出时，我注意到提取不会从数据库中检索所有值 - 只有那些状态值为 1 的值。我在下面包含了核心代码。如果有人能够帮助我找到解决方案，或者解释我的问题的根本原因，我将不胜感激，谢谢！

create or replace procedure FLEX_SUMMARY_STATUS_PROCEDURE as

old_panel_status number;
new_panel_status number;

cursor panel_cursor is
    select FLEX_PANEL_STATUS
    from FLEX_PANEL_INSPECTIONS;

begin

    open panel_cursor;
    loop

        fetch panel_cursor into old_panel_status;
        exit when panel_cursor%notfound;

        if old_panel_status = 0
            then new_panel_status := 2;
        elsif old_panel_status = 1
            then new_panel_status := 3;
        --More conditional loops follow (but are irrelevant for this question).

        dbms_output.put_line(old_panel_status);
        --Test output
        --This displays all of the 1's that were randomly generated in the original table.
        --It does not display any of the 0's that were generated.

        end if;
    end loop;

close panel_cursor;
close sensor_cursor;

end FLEX_SUMMARY_STATUS_PROCEDURE;
/

Answer 1

如果您在删除额外的 elseif 子句时没有犯错，那么问题出在您的 dbms_output.put_line。

它位于else部分内部，因此只有在调用该子句时才会触发。将它移到 END IF 下方并确保使用正确的缩进，这样更容易发现这些东西。

create or replace procedure FLEX_SUMMARY_STATUS_PROCEDURE as

old_panel_status number;
new_panel_status number;

cursor panel_cursor is
    select FLEX_PANEL_STATUS
    from FLEX_PANEL_INSPECTIONS;

begin

    open panel_cursor;
    loop

        fetch panel_cursor into old_panel_status;
        exit when panel_cursor%notfound;

        if old_panel_status = 0
            then new_panel_status := 2;
        elsif old_panel_status = 1
            then new_panel_status := 3;
        --More conditional loops follow (but are irrelevant for this question)
        end if;

    dbms_output.put_line(old_panel_status);

    end loop;

    close panel_cursor;
    close sensor_cursor;

end FLEX_SUMMARY_STATUS_PROCEDURE;
/

Answer 2

除了已经在接受的答案中修复的主要错误之外，下面的代码还显示了更新的循环结构。您可以选择您喜欢的任何变量名称，而不是 rec。在每次迭代中，它包含一行（通常不止一列）。

create or replace procedure FLEX_SUMMARY_STATUS_PROCEDURE as

new_panel_status number;

cursor panel_cursor is
    select FLEX_PANEL_STATUS
    from FLEX_PANEL_INSPECTIONS;

begin

    for rec in panel_cursor loop

        if rec.flex_panel_status = 0 then
            new_panel_status := 2;
        elsif rec.flex_panel_status = 1 then
            new_panel_status := 3;
        --More conditional loops follow (but are irrelevant for this question)
        end if;

        dbms_output.put_line(rec.flex_panel_status);

    end loop;

end FLEX_SUMMARY_STATUS_PROCEDURE;
/

如果你愿意，你甚至可以摆脱显式光标：

for rec in (
    select FLEX_PANEL_STATUS
    from FLEX_PANEL_INSPECTIONS
) loop

为什么我的显式游标仅从 PL/SQL 中的数据库中提取特定行？

Why does my explicit cursor fetch only specific rows from my database in PL/SQL?

sql

oracle

plsql

cursor

fetch