为什么我的代码不起作用？ （使用多表达式+强制转换+案例）

Question

我的专栏示例：

          (name) as varchar(50)
              s01
              s02
              s16

我想选择第一个缺少0以上的面板名称也使用case和cast（在我的例子中所需的select将是's03'）

WITH cte AS(
    SELECT name 
    FROM customers 
    UNION ALL 
    SELECT 0
) 

SELECT  CASE WHEN cast(min(right(name, 2) + 1) as varchar(50)) < 10 THEN 's0' ELSE 's' END + 
        cast(min(right(name, 2) + 1) as varchar(50)) 
FROM cte 
WHERE NOT EXISTS ( 
    SELECT name 
    FROM customers  
    WHERE cast(right(customers.name, 2) as varchar(50)) = cast(right(cte.name, 2) as varchar(50))+1) 

此代码有效但仅在我的表为空或表仅包含数字的情况下。

示例我的列名称＆gt;结果将是s03

             1     or   101    
             2          102
             16         116

但是当它包含字母

时

 example my columns in name
             s01         
             s02
             s016

它不起作用。我收到一个错误：将varchar值's01'转换为数据类型int时转换失败。我应该把其他地方转换为varchar吗？

Answer 1

（代表OP发布）。

只需转换联合选择。

    WITH cte AS(
    SELECT name 
    FROM customers 
    UNION ALL 
    SELECT CAST(0 AS VARCHAR(50)) 
    FROM INVENTORYPANELCAPTIONS
) 

SELECT  CASE WHEN  cast(min(right(name, 2) + 1) as varchar(50)) < 10 THEN 's0' ELSE 's' END 
        + cast(min(right(name, 2) + 1) as varchar(50)) 
FROM cte 
WHERE NOT EXISTS ( 
    SELECT name 
    FROM customers 
    WHERE right(customers.name, 2)= right(cte.name, 2)+1) 

Answer 2

您正在将字符串（varchar）与int值进行比较，因此在将intchar值与int值进行比较或对它们执行某些操作之前，请尝试将varchar数字转换为int而不是varchar

也许这样的事情（不确定这是否会起作用，但只是将其作为示例写出解决方案的外观）：

WITH cte AS(SELECT panelname FROM inventorypanelcaptions UNION ALL SELECT 0) 
SELECT CASE WHEN min(cast(right(panelname, 2) as int)) + 1 < 10 THEN 'o0' ELSE 'o' + cast(min(cast(right(panelname, 2) as int)) + 1 as varchar(50)) END
FROM cte 
WHERE NOT EXISTS (SELECT panelname FROM inventorypanelcaptions WHERE cast(right(inventorypanelcaptions.panelname, 2) as int) = cast(right(cte.panelname, 2) as int) + 1)