mysql concat删除尾部破折号（如果存在）

Question

我有一个选择，它将多个列连接在一起，用短划线“ - ”字符分隔它们。最后一列“描述”可能有也可能没有值。如果确实如此，一切都很好，如果没有，我最后会得到一个“ - ”。如果它是“ - ”，我怎么能摆脱最后一个字符？

SELECT CONCAT(locationid,'-',city,'-',state,'-',country,'-',description) FROM sys_locations ORDER BY locationid

填充'description'列的示例： AUC01极光-CO-US-DC

'description'列为空的示例： AUM01-Auburn Hills-MI​​-US-＆lt; - notice trailing dash。

谢谢， 大卫

Answer 1

您需要NULLIF：

SELECT CONCAT_WS('-', locationid, city, state, country, NULLIF(description, '')) 
FROM sys_locations ORDER BY locationid

Answer 2

你可以这样做

SELECT CONCAT(locationid,'-',city,'-',state,'-',country,IF(description is null,'',concat('-', description))) FROM sys_locations ORDER BY locationid

Answer 3

要处理NULL和＆＃39;＆＃39;，请尝试：

SELECT CONCAT(locationid,'-', city, '-', state, '-', country, case when description IS NULL or description = '' then '' else '-' end, description)
FROM sys_locations ORDER BY locationid