存储过程输出字符串和光标

Question

嘿家伙，我有一个存储过程，只输出表的列。相反，我想'有''专栏''的学生。'作为输出。下面的例子。

CREATE OR REPLACE PROCEDURE active_students (arc in out sys_refcursor) 
     as 
     begin 
      open arc for select count(*) from student; 
     end; 

这产生

Count(*) 
30 

想它来阅读

There are 30 students. 

Answer 1

用途：

CREATE OR REPLACE PROCEDURE JSU4290M.active_students (arc in out sys_refcursor) 
AS 
BEGIN 

    OPEN arc FOR 
    SELECT 'There are '|| COUNT(*) ||' students.' AS col 
    FROM STUDENT; 

END; 

双管（||）是Oracle（现在ANSI标准）连接字符串的方式。 Oracle会将整数值隐式转换为一个字符串。