基于sql server中索引位置的字符串提取

Question

我们可以根据索引位置从字符串中获取字符吗？

例子：有一个字符串“ABCDEFGHIJKLMNOPQR”

我想提取其在偶数位置的所有字符。

Answer 1

根据@Aishvarya和@Arvo的建议，代码如下所示。很简单。

declare @input varchar(100) = 'ABCDEFGHIJKLMNOPQR' 
declare @output varchar(100) = '' 

declare @index int = 1 
declare @max_index int = (select len(@input)) 

while @index <= @max_index 
begin 
    if @index % 2 = 0 
     set @output = @output + substring(@input, @index, 1) 

    set @index = @index + 1 
end 

print @output -- BDFHJLNPR 

Answer 2

指数从1开始在SQL所以用Substring

SELECT SUBSTRING('ABCDEFGHIJKLMNOPQR', 1, 1) //returns the character at 2nd position 
SELECT SUBSTRING('ABCDEFGHIJKLMNOPQR', 3, 1) //returns the character at 4th position 

等。