sql - T-SQL - 逐字符比较字符串

Question

我需要使用 T-SQL 逐个字符地比较两个字符串。假设我有两个这样的字符串:

123456789    
212456789

每次字符不匹配时，我想增加变量@Diff +=1。在这种情况下，前三个字符不同。所以@Diff = 3(0 是默认值)。

感谢您的所有建议。

Answer 1

对于表格中您不想使用逐行方法的列，试试这个:

with cte(n) as (
    select 1
    union all
    select n + 1 from cte where n < 9
)
select
    t.s1, t.s2,
    sum(
      case
      when substring(t.s1, c.n, 1) <> substring(t.s2, c.n, 1) then 1
      else 0
      end
    ) as diff
from test as t
    cross join cte as c
group by t.s1, t.s2

=>sql fiddle demo