sql-server - 用 TSQL 替换字符串中的每个字符的第二个实例

我有一个字段，其中包含一串定义地理围栏(多边形)的纬度/经度坐标。每个都用逗号分隔。

例如:'纬度，经度，纬度，经度，经度，经度'
例如:148.341158，-21.500773,148.341406，-21.504989,148.375136，-21.513174,148.401674，-21.535247,148.418044，-21.532767,148.408867，-21.511685,148.414075，-21.508461,148.36968，-21.432567,148.349094，-21.438768,148.346862， - 21.480187,148.341158,-21.500773,

我想在 MSSQL ( http://msdn.microsoft.com/en-us/library/bb933971.aspx ) 中使用地理类型

DECLARE @g geography;
SET @g = geography::STPolyFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326);
SELECT @g.ToString();

这似乎需要:'lat long, lat long, lat long' 即:这对之间没有逗号。

我无法更改源数据，因为它被供应商程序使用。我需要操作字符串以删除每 2 个逗号中的 1 个，或者失败，让正则表达式在 TSQL 中工作

最佳答案

你可以像下面这样滚动你自己的解析器。它使用字符串中的逗号来查找所有纬度/经度值。它使用以下模式将所有值连接在一起:lat long, lat long, ...

declare @list varchar(max)
declare @result varchar(max)
declare @word varchar(max)
declare @splitOn varchar(1)
declare @wpos int
declare @cpos int
declare @wordCount int

select @list = '148.341158,-21.500773,148.341406,-21.504989,148.375136,-21.513174,148.401674,-21.535247,148.418044,-21.532767,148.408867,-21.511685,148.414075,-21.508461,148.36968,-21.432567,148.349094,-21.438768,148.346862,-21.480187,148.341158,-21.500773,'
select @splitOn = ','
select @result = ''

select @cpos = 0
select @wpos = 1
select @wordCount = 1

while (@cpos <= len(@list))
begin
    select @cpos = charindex(@splitOn, @List, @cpos)
    if (@cpos < 1) select @cpos = len(@list) + 1

    select @word = substring(@list, @wpos, @cpos - @wpos)
    select @result = @result + ' ' + @word

    if ((@wordCount % 2) = 0 and (@cpos < len(@list))) select @result = @result + ','

    select @cpos = @cpos + 1
    select @wpos = @cpos
    select @wordCount = @wordCount + 1
end
select @result as result

它产生以下字符串:

关于sql-server - 用 TSQL 替换字符串中的每个字符的第二个实例，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/19148161/