问题描述
由于我的作业需要我使用存储过程,我想打印出表中的数据,但它只显示(PL/sql 过程成功完成。)但没有打印出任何数据。以下是我的代码:
CREATE OR REPLACE PROCEDURE showMenu(Merchant_N IN Varchar2)
AS
Food_Name Varchar2(30) := null;
BEGIN
SELECT Food_Name
INTO Food_Name
From Food,Merchant
Where Merchant_Name = Merchant_N AND
Merchant.Merchant_ID = Food.Merchant_ID;
dbms_output.enable;
dbms_output.put_line('The food is');
dbms_output.put_line(Food_Name);
END;
EXEC showMenu(‘KFC’)
解决方法
set serveroutput on
将 serveroutput 设置为 on 然后再次执行 proc 然后你应该看到一个输出
,对于您的第二个问题 - 处理多行:
CREATE OR REPLACE PROCEDURE showMenu(Merchant_N IN Varchar2)
AS
Food_Name Varchar2(30) := null;
BEGIN
for x in (SELECT Food_Name
-- INTO Food_Name not needed for cursor loops
From Food,Merchant
Where Merchant_Name = Merchant_N AND
Merchant.Merchant_ID = Food.Merchant_ID)
loop
-- dbms_output.enable; < not needed
dbms_output.put_line('The food is');
dbms_output.put_line(x.Food_Name); --
end loop;
END;
你真的想要两行吗?怎么样
loop
dbms_output.put_line('The food is '|| x.Food_Name);
end loop;
你真的应该使用 ANSI 连接语法:
From Food
join Merchant on Food.Merchant_ID = Merchant.Merchant_ID
Where Merchant_Name = Merchant_N