Question

我想从MySQL表中检索数据并将其格式化为“Bruno，Phil Sturgeon和Simon”。具体来说，我想用逗号连接所有值，除了最后一个，我想用“和”连接。

现在我只能用逗号连接所有值。如何用“和”代替最后一个实例？

这是我的问题：

SELECT
   b.title,
   GROUP_CONCAT(a.name ORDER BY name SEPARATOR ',') AS name                   
FROM `book` AS b
LEFT JOIN `book_authors` AS ba
  ON b.id = ba.book_id
INNER JOIN `author` AS a
  ON a.id = ba.author_id
GROUP BY b.id
ORDER BY b.title

Answer 1

取值到最后一个逗号，CONCAT为'AND'，然后添加最后一个值

SELECT
   b.title,
  CONCAT(SUBSTRING_INDEX( GROUP_CONCAT(a.name ORDER BY name SEPARATOR ','),',',length( GROUP_CONCAT(a.name ORDER BY name SEPARATOR ','))-length(replace( GROUP_CONCAT(a.name ORDER BY name SEPARATOR ','),',',''))),
              ' AND ',SUBSTRING_INDEX( GROUP_CONCAT(a.name ORDER BY name SEPARATOR ','),',',-1)) AS name                   
FROM `book` AS b
LEFT JOIN `book_authors` AS ba
  ON b.id = ba.book_id
INNER JOIN `author` AS a
  ON a.id = ba.author_id
GROUP BY b.id
ORDER BY b.title

Here它是硬编码的

Answer 2

“用户定义变量”，CONCAT和SUBSTRING_INDEX功能的优化解决方案。
这将立即调用GROUP_CONCAT，并且仅使用变量@name执行进一步的操作：

SET @name = "";
SELECT CONCAT(LEFT(@name, LENGTH(@name) - LENGTH(SUBSTRING_INDEX(@name,',',-1))-1), ' and ', SUBSTRING_INDEX(@name, ',', -1)) name, title
FROM
(SELECT
   b.title as title,
   @name:= GROUP_CONCAT(a.name ORDER BY name SEPARATOR ',') AS name                   
FROM `book` AS b
LEFT JOIN `book_authors` AS ba
  ON b.id = ba.book_id
INNER JOIN `author` AS a
  ON a.id = ba.author_id
GROUP BY b.id
ORDER BY b.title) as t;

在GROUP_CONCAT mysql中用AND替换最后一个逗号

2 个答案: