如何將多個列值連接成一個列？

Question

我有以下表格朋友

id | first_name | last_name | gender | age | mobile 
1 | bobby  | roe  | male | 21 | 541-5780 

如何連接多列（FIRST_NAME &姓氏）值成一列得到以下結果呢？

full_name 
bobby roe 

我已經writen下面的查詢，但它不工作

declare @full_name varchar(max) 
select @full_name = COALESCE(@full_name + ', ', '') + first_name, last_name 
from friend 
select @full_name 

Answer 1

不止一個的方式來實現這一目標：

SELECT CONCAT(first_name, ' ' ,last_name) AS full_name; 

對於早期版本（其中CONCAT是不是內置功能）：

SELECT first_name + ISNULL(' ' + last_name, '') as Full_Name from [YourTable] 

這也應該給你同樣的結果

SELECT COALESCE(first_name, '') + COALESCE(last_name, '') as FullName FROM [YourTable]