基本的SQL问题(将varchar值"转换为int数据类型时，转换失败.) [英] Basic SQL problem (Conversion failed when converting the varchar value '' to data type int.)

问题描述

我正在尝试使此查询非常简单，但与我和SQL一样，它始终不起作用.

Hi,

I''m trying to get this fairly easy query to work but, as always with me and SQL, it doesn''t work.

(
SELECT 
   (
      CASE WHEN FotoId IS NULL 
      THEN ''Some URL''
      ELSE ''Some URL'' + FotoId + ''-100-100-9.jpg''
      END
   ) AS FotoURL
FROM Fotos
WHERE ProfielId = 123

错误:

ERROR:

Msg 245, Level 16, State 1, Line 1
Conversion failed when converting the varchar value ''Some URL'' to data type int.

推荐答案

这是因为您试图连接字符串和整数-您需要将整数转换为字符串:

It''s because you are trying to concatenate a string and an int - you need to convert the int to a string:

ELSE 'Some URL' + CONVERT(NVARCHAR(10), FotoId) + '-100-100-9.jpg'

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