如何在 mySQL 中使用嵌套案例？

Question

我想处理嵌套案例：

SELECT *, 
    GROUP_CONCAT(DISTINCT CONCAT(
    CASE
      WHEN data.name NOT "field" THEN   
        CASE
          WHEN data.category = "A" THEN "A"
          WHEN data.category = "B" THEN "B"
          ELSE "C"
        END,data.name
    END
   )ORDER BY FIND_IN_SET(data.category,"B,C,A") ASC, data.name ASC SEPARATOR " <br>") AS result
  FROM data;');

但我收到一条错误消息：

Fatal error: Uncaught PDOException: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'data.name END ' at line 11

Answer 1

您的查询中存在一些语法错误。运行在您的查询编辑器中输入以下代码，就可以了。

SELECT 
 *,
GROUP_CONCAT(
DISTINCT CONCAT(
  CASE
    WHEN data.name = "field" 
    THEN (
      CASE
        WHEN data.category = "A" 
        THEN "A" 
        WHEN data.category = "B" 
        THEN "B" 
        ELSE "C" 
      END
    ) 
  END,
    data.name
) 
ORDER BY FIND_IN_SET(data.category, "B,C,A") ASC,
data.name ASC SEPARATOR " <br>"
) AS result 
 FROM DATA;

如何在 mySQL 中使用嵌套案例？

How can I use nested cases in mySQL?

mysql

if-statement

nested

group-concat