Sql查询结果问题

Question

我想检索这个列值的第二个字，但它显示空白。

我的查询是：

select ltrim(
    substring(companyname, 
    charindex(' ',companyname), 
    CHARINDEX(
    ' ', 
    ltrim(
     SUBSTRING(
     companyname, 
     charindex(' ',companyname), 
     LEN(companyname) - charindex(' ',companyname)) 
    ) 
    ) 
) 
) 
from pmweb_companies 
where companyname = '7x24 Exchange' 

结果应该返回：交易所 但它显示空白。

Answer 1

这是因为该查询要求总词数超过两个，这意味着在分析的字符串中至少需要两个空格。

如果要排除的第一个字和得到的第二个字什么，你可以使用类似这样

select ltrim(
     substring(
      companyname, 
      charindex(' ', companyname), 
      len(companyname) - charindex(' ', companyname) + 1 
     ) 
     ); 

如果你想要的是第二个字来代替，就可以破解您查询到这个

select ltrim(
    substring(companyname, 
    charindex(' ', companyname), 
    CHARINDEX(
    ' ', 
    ltrim(
     SUBSTRING(
     companyname + ' fake', 
     charindex(' ', companyname), 
     LEN(companyname + ' fake') - charindex(' ', companyname)) 
    ) 
    ) 
) 
) 
from pmweb_companies 
where companyname = '7x24 Exchange' 

编辑

如果我正确理解你的评论，如果字符串只有一个字，该查询应该返回空白。如果是这样的话，你可以使用一个case语句进行select

select case 
      when charindex(
       ' ', 
       substring(
        companyname, 
        charindex(' ', companyname), 
        LEN(companyname) - charindex(' ', companyname) + 1 
       ) 
       ) = 0 /* this means there's less than two words */ 
      then '' /* you can place something else here, as you prefer */ 
      else 
      ltrim(
       substring(companyname, 
       charindex(' ', companyname), 
       CHARINDEX(
       ' ', 
       ltrim(
        SUBSTRING(
        companyname + ' fake', 
        charindex(' ', companyname), 
        LEN(companyname + ' fake') - charindex(' ', companyname)) 
       ) 
       ) 
      ) 
      ) 
      end 
from pmweb_companies 
where companyname = '7x24 Exchange'