选择 concat(first_name,' ',last_name) 作为员工的“全名”---在 oracle 中连接 2 列时如何带空间---

Question

select concat(first_name,' ',last_name) as "full name "from employees

Answer 1

Oracle's CONCAT function takes only two arguments. So if you wanted to continue along with your exact current approach, you would have to chain together two calls to CONCAT :

SELECT CONCAT(CONCAT(first_name, ' '), last_name) AS "full name"
FROM employees;

Or, you could just use the ANSI standard concatenation operator || :

SELECT first_name || ' ' || last_name AS "full name"
FROM employees;

Answer 2

Use the operator || :

select (first_name || ' ' || last_name) as full_name
from employees

Answer 3

Check the below using ||

 select first_name || ' ' || last_name as "full name" from employees;

If you want to use CONCAT operator you can try the below:

SELECT CONCAT(CONCAT(first_name , ' '),LAST_NAME) AS "full name"
      FROM employees;