MySQL将地址转换为逗号分隔的字符串

是否有任何方法可以缩短/更容易地读取以下SQL以连接字符串

SELECT
   CONCAT(       
    IF(location_address1 != '',
       CONCAT(location_address1, ", "),
       ""
    ),
    IF(location_address2 != '',
       CONCAT(location_address2, ", "),
       ""
    ),
    IF(location_town != '',
       CONCAT(location_town, ", "),
       ""
    ),
    IF(location_region != '',
       CONCAT(location_region, ", "),
       ""
    ),
    IF(location_postcode != '',
       CONCAT(location_postcode, ", "),
       ""
    ),
    c.country_name
   )      
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1

不跳过空字符串。但是，它会跳过分隔符参数之后的任何空值

如果expr1=expr2为真，则返回NULL，否则返回expr1

因此，您的查询可能是：

SELECT 
  CONCAT_WS(', ', 
       NULLIF(location_address1, ''),
       NULLIF(location_address2, ''),
       NULLIF(location_town, ''), 
       NULLIF(location_region, ''), 
       NULLIF(location_postcode, ''), 
       NULLIF(country_name, '')
  ) AS address
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1

不跳过空字符串。但是，它会跳过分隔符参数之后的任何空值

如果expr1=expr2为真，则返回NULL，否则返回expr1

因此，您的查询可能是：

SELECT 
  CONCAT_WS(', ', 
       NULLIF(location_address1, ''),
       NULLIF(location_address2, ''),
       NULLIF(location_town, ''), 
       NULLIF(location_region, ''), 
       NULLIF(location_postcode, ''), 
       NULLIF(country_name, '')
  ) AS address
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1

您可以将MySQL中的函数用作：

SELECT CONCAT_WS(',',IF(location_address1 = '', NULL, location_address1),
                     IF(location_address2 = '', NULL, location_address2),
                     IF(location_town = '', NULL, location_town),
                     IF(location_region = '', NULL, location_region),
                     IF(location_postcode = '', NULL, location_postcode),
                     c.country_name)  AS str
FROM countries c
WHERE c.country_id = locations.country_id
LIMIT 1;

甚至@CyberDem0n建议的简单方法：

SELECT CONCAT_WS(',',NULLIF(location_address1,''),
                     NULLIF(location_address2,''),
                     NULLIF(location_town,''),
                     NULLIF(location_region,''),
                     NULLIF(location_postcode,''),
                     c.country_name)  AS str
FROM countries c
WHERE c.country_id = locations.country_id
LIMIT 1;

但是，如果您可以存储空值而不是空值，这将是更好的方法。

您可以将MySQL中的函数用作：

SELECT CONCAT_WS(',',IF(location_address1 = '', NULL, location_address1),
                     IF(location_address2 = '', NULL, location_address2),
                     IF(location_town = '', NULL, location_town),
                     IF(location_region = '', NULL, location_region),
                     IF(location_postcode = '', NULL, location_postcode),
                     c.country_name)  AS str
FROM countries c
WHERE c.country_id = locations.country_id
LIMIT 1;

甚至@CyberDem0n建议的简单方法：

SELECT CONCAT_WS(',',NULLIF(location_address1,''),
                     NULLIF(location_address2,''),
                     NULLIF(location_town,''),
                     NULLIF(location_region,''),
                     NULLIF(location_postcode,''),
                     c.country_name)  AS str
FROM countries c
WHERE c.country_id = locations.country_id
LIMIT 1;

但是，如果您可以存储空值而不是空值，这将是更好的方法

我没有检查语法，但我的想法是，与其检查每个语法是否为null或空，不如始终使用连接，然后将所有、替换为、

我没有检查语法，但我的想法是，与其检查每个语法是否为null或空，不如按照@Xdazz的要求，始终使用连接，然后将所有、替换为、。

此修剪版本：

SELECT 
  CONCAT_WS(', ', 
       NULLIF(Trim(location_address1), ''),
       NULLIF(Trim(location_address2), ''),
       NULLIF(Trim(location_town), ''), 
       NULLIF(Trim(location_region), ''), 
       NULLIF(Trim(location_postcode), ''), 
       NULLIF(Trim(country_name), '')
  ) AS address
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1

根据@Xdazz

此修剪版本：

SELECT 
  CONCAT_WS(', ', 
       NULLIF(Trim(location_address1), ''),
       NULLIF(Trim(location_address2), ''),
       NULLIF(Trim(location_town), ''), 
       NULLIF(Trim(location_region), ''), 
       NULLIF(Trim(location_postcode), ''), 
       NULLIF(Trim(country_name), '')
  ) AS address
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1

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如果位置\地址1=，NULL，位置\地址1可替换为NULL位置\地址1，如果位置\地址1=，NULL，位置\地址1可替换为NULL位置\地址1，