在连接列同时跳过 NULL 值后在 SQL 查询返回中插入换行符答案

【问题标题】：Insert line break into SQL query return after concatenating columns whilst skipping NULL values在连接列同时跳过 NULL 值后在 SQL 查询返回中插入换行符
【发布时间】：2017-03-20 10:29:50
【问题描述】：

我想将几列连接在一起，并在考虑NULL 值的情况下用换行符分隔每列返回。

比如我有如下数据表（[dbo].[Address]）：

Name         Address_line1    Address_line2   Address_line 3   Postcode
Mr Smith     1 Smith Street   NULL            Ireland          AB1 1CD
Mr Jones     1 Jones Road     Wales           NULL             EF2 3GH
Mrs White    1 White Way      England         UK               NULL

我想返回以下内容：

Name         Address
Mr Smith     1 Smith Street,
             Ireland,
             AB1 1CD
Mr Jones     1 Jones Road,
             Wales,
             EF2 3GH
Mrs White    1 White Way,
             England,
             UK

我该怎么做？

【问题讨论】：

你可以在表现层处理这个

标签： sql sql-server concatenation

【解决方案1】：

你试过了吗？

select name,
       replace(stuff( coalesce('[sep]' + address_line1, '') +
                      coalesce('[sep]' + address_line2, '') +
                      coalesce('[sep]' + address_line3, ''),
                      1, 5, ''
                    ), '[sep]', '
'
               )
. . .

【讨论】：

【解决方案2】：

您可以使用+ 运算符和COALESCE() 的组合：

WITH T AS (SELECT 'Mr Smith' AS NAME, '1 Smith Street' AS Address_Line1, NULL AS Address_line2, 'Ireland' AS Address_Line3, 'AB1 1CD' AS PostCode
UNION SELECT 'Mr Jones' AS NAME, '1 Jones Road' AS Address_Line1, 'Wales' AS Address_line2, NULL AS Address_Line3, 'EF2 3GH' AS PostCode
UNION SELECT 'Mrs White' AS NAME, '1 White Way' AS Address_Line1, 'England' AS Address_line2, 'UK' AS Address_Line3, NULL AS PostCode
)
  SELECT NAME, ADDRESS_LINE1  
+ COALESCE(','+ CHAR(13)+CHAR(10)  + Address_line2 , '') 
+ COALESCE ',' + (CHAR(13)+CHAR(10)  +Address_line3 ,'')
+ COALESCE(',' + CHAR(13)+CHAR(10) +POSTCODE,'') AS ADDRESS
FROM T

输出：

NAME      
--------- --------------------------------------------
Mr Jones  1 Jones Road,
   Wales,
   EF2 3GH
Mr Smith  1 Smith Street,
   Ireland,
   AB1 1CD
Mrs White 1 White Way,
   England,
   UK

【讨论】：

与字符的连接不会使空值不为空吗？
不，但我必须编辑我的查询，因为我没有看到 POSTCODE 可以为 NULL，我必须消除挂起的 ','
完成了。 @Stefano：在genere è il contrario：setenti di concatenare stringa con NULL, ottieni NULL。

【解决方案3】：

你可以用CHAR(13)点赞

select Name, 
Address_line1 + ',' +char(13) + Address_line2 + ',' + char(13) + Address_line 3 as address 
from [dbo].[Address]

【讨论】：

【解决方案4】：

我更喜欢将 ISNULL() 与 Char (13) + CHAR(10) 一起使用：

SELECT 
Name 
, ISNULL(Address_line1 + ',' + CHAR(13)) + CHAR(10), '') + ISNULL(Address_line2 + ',' + CHAR(13)) + CHAR(10), '') + ISNULL(Address_line 3, '') as address 
from [dbo].[Address]

【讨论】：

【解决方案5】：

SELECT 
name, 
CONCAT(
COALESCE(Address_line1,''), ', ', 
COALESCE(Address_line2,''), ', ', 
COALESCE(Address_line3,''), ', ', 
COALESCE(Postcode,'')
) AS address 
FROM table_name;

【讨论】：

请评论您提供的代码，帮助理解您的建议。