Oracle多列单别名

Question

我正在尝试选择多个列，并在Oracle 11.2.0.1.0中将此列连接在一个带有加号的列中，并且在此加号的两侧都留有一个空格

SELECT ename AS Emplyee_name , deptno AS Department_Number , comm+" + " + sal AS This_Month_Comm_and_sal FROM emp WHERE ename = 'AHMAD';

我收到此错误

ORA-00904：“ +”：无效的标识符

在此w3schools教程W3schools SQL教程中也是如此

如何在ORACLE中获得相同的结果？

Answer 1

字符串连接运算符为|| 在Oracle中：在这里必须使用单引号。

SELECT 
    ename AS Emplyee_name , 
    deptno AS Department_Number , 
    TO_CHAR(comm) || ' + ' || TO_CHAR(sal) AS This_Month_Comm_and_sal 
FROM emp 
WHERE ename = 'AHMAD';