传递给LEFT或SUBSTRING函数的无效长度参数(SQL Server)

Question

我有这个问题:

CASE
   WHEN ISNUMERIC(SUBSTRING(dbo.Post.OdaSayisi, 1, CHARINDEX('+', dbo.Post.OdaSayisi) - 1)) = 1 
      THEN SUBSTRING(dbo.Post.OdaSayisi, 1, CHARINDEX('+', dbo.Post.OdaSayisi) - 1)
      ELSE 0
END AS RoomNumber,

where OdaSayisi是一个像3 + 1,4 + 2的字符串.当我尝试编写此查询时:

SELECT *
FROM [myDB].[dbo].[MyView] 
WHERE RoomNumber = 3

我在标题中收到此错误.我怎样才能解决这个问题？谢谢.

Answer 1

问题是某些值OdaSayisi没有'+'.最简单的解决方案是将一个用于CHARINDEX()功能

(CASE WHEN ISNUMERIC(SUBSTRING(dbo.Post.OdaSayisi, 1, CHARINDEX('+', dbo.Post.OdaSayisi + '+') - 1)) = 1
      THEN SUBSTRING(dbo.Post.OdaSayisi, 1, CHARINDEX('+', dbo.Post.OdaSayisi + '+') - 1)
      ELSE 0
 END) AS RoomNumber,

在+ '+'确保CHARINDEX()不会返回一个负数.