SQL中替换字符串中连续空格为一个空格的方法：

http://www.sqlservercentral.com/articles/T-SQL/68378/

O

OO

OOO

OOOO

OOOOO

OOOOOO

OOOOOOO

OOOOOOOO

第一步：把OO替换为OX

O

OX

OXO

OXOX

OXOXO

OXOXOX

OXOXOXO

OXOXOXOX

第二步：把XO替换为空

O

OX

O

OX

O

OX

O

OX

第三步：把X替换为空

O

O

O

O

O

O

O

O

DECLARE @Demo TABLE(OriginalString VARCHAR(8000))

 INSERT INTO @Demo (OriginalString)

 SELECT ' This has multiple unknown spaces in it. ' UNION ALL

 SELECT 'So does this!' UNION ALL

 SELECT 'As does this' UNION ALL

 SELECT 'This, that, and the other thing.' UNION ALL

 SELECT 'This needs no repair.'

--===== Reduce each group of multiple spaces to a single space

     -- for a whole table without functions, loops, or other

     -- forms of slow RBAR. In the following example, CHAR(7)

     -- is the "unlikely" character that "X" was used for in 

     -- the explanation.

 SELECT REPLACE(

            REPLACE(

                REPLACE(

                    LTRIM(RTRIM(OriginalString))

                ,' ',' '+CHAR(7)) --Changes 2 spaces to the OX model

            ,CHAR(7)+' ','') --Changes the XO model to nothing

        ,CHAR(7),'') AS CleanString --Changes the remaining X's to nothing

   FROM @Demo

  WHERE CHARINDEX(' ',OriginalString) > 0