Sql server SQL server替换可变数量的内部空白，并替换为一个空格

我一直在寻找一种方法，用SQL查询中的单个空格替换字符串之间的所有空白。我已经找到了很多要替换的引用，除了要替换的字符串必须精确之外，这些引用都可以正常工作

我怎样才能改变

Bob     Jones to Bob Jones
Jim Jones to remain the same
Jeff         Jones to Jeff Jones

谢谢你的帮助

DECLARE @String1 VARCHAR(1000) = 'Jeff         Jones to Jeff       Jones'
DECLARE @String2 VARCHAR(1000) = 'Bob     Jones to   Bob        Jones'

SELECT REPLACE(REPLACE(REPLACE(@String1,'  ',' '+CHAR(1)) ,CHAR(1)+' ',''),CHAR(1),'') AS Col

SELECT REPLACE(REPLACE(REPLACE(@String2,'  ',' '+CHAR(1)) ,CHAR(1)+' ',''),CHAR(1),'') AS Col

结果

Col
Jeff Jones to Jeff Jones

Col
Bob Jones to Bob Jones

用户定义功能

CREATE FUNCTION udf_ReplaceWhiteSpace(@String NVARCHAR(MAX))
RETURNS NVARCHAR(MAX)
AS
BEGIN
   DECLARE @RtnString NVARCHAR(MAX);

    SET @RtnString = REPLACE(REPLACE(REPLACE(@String,'  ',' '+CHAR(1)) ,CHAR(1)+' ',''),CHAR(1),'');

  RETURN @RtnString;
END

UDF测试

DECLARE @String VARCHAR(1000) = 'Jeff         Jones    to  Jones till       the       end'


SELECT dbo.udf_ReplaceWhiteSpace(@String) 

Jeff Jones to Jones till the end

返回的结果

DECLARE @String VARCHAR(1000) = 'Jeff         Jones    to  Jones till       the       end'


SELECT dbo.udf_ReplaceWhiteSpace(@String) 

Jeff Jones to Jones till the end

---

有几种方法可以实现这一点，您选择实现哪种方法主要取决于每种方法的性能

这里详细介绍了所有方法：通过

这里是第一个方法，它使用递归。我已经更新了示例代码以满足您的需求

方法1-代码（功能）：

CREATE FUNCTION dbo.RemoveMultipleSpaces (@str NVARCHAR(MAX))
    RETURNS NVARCHAR(MAX)
AS
BEGIN
    IF CHARINDEX('  ', @str) = 0
        RETURN @str;

    RETURN dbo.RemoveMultipleSpaces(REPLACE(@str, '  ', ' '));
END
GO

DECLARE @s VARCHAR(MAX) = 'Bob     Jones';
DECLARE @s1 VARCHAR(MAX) = 'Jim Jones';
DECLARE @s2 VARCHAR(MAX) = 'Jeff         Jones';
SELECT @s as BeforeString, dbo.RemoveMultipleSpaces(@s) AS AfterString
UNION
SELECT @s1 as BeforeString, dbo.RemoveMultipleSpaces(@s1) AS AfterString
UNION
SELECT @s2 as BeforeString, dbo.RemoveMultipleSpaces(@s2) AS AfterString

BeforeString              AfterString

Bob     Jones             Bob Jones
Jim Jones                 Jim Jones
Jeff         Jones        Jeff Jones

方法1示例：

CREATE FUNCTION dbo.RemoveMultipleSpaces (@str NVARCHAR(MAX))
    RETURNS NVARCHAR(MAX)
AS
BEGIN
    IF CHARINDEX('  ', @str) = 0
        RETURN @str;

    RETURN dbo.RemoveMultipleSpaces(REPLACE(@str, '  ', ' '));
END
GO

DECLARE @s VARCHAR(MAX) = 'Bob     Jones';
DECLARE @s1 VARCHAR(MAX) = 'Jim Jones';
DECLARE @s2 VARCHAR(MAX) = 'Jeff         Jones';
SELECT @s as BeforeString, dbo.RemoveMultipleSpaces(@s) AS AfterString
UNION
SELECT @s1 as BeforeString, dbo.RemoveMultipleSpaces(@s1) AS AfterString
UNION
SELECT @s2 as BeforeString, dbo.RemoveMultipleSpaces(@s2) AS AfterString

BeforeString              AfterString

Bob     Jones             Bob Jones
Jim Jones                 Jim Jones
Jeff         Jones        Jeff Jones

方法1结果：

CREATE FUNCTION dbo.RemoveMultipleSpaces (@str NVARCHAR(MAX))
    RETURNS NVARCHAR(MAX)
AS
BEGIN
    IF CHARINDEX('  ', @str) = 0
        RETURN @str;

    RETURN dbo.RemoveMultipleSpaces(REPLACE(@str, '  ', ' '));
END
GO

DECLARE @s VARCHAR(MAX) = 'Bob     Jones';
DECLARE @s1 VARCHAR(MAX) = 'Jim Jones';
DECLARE @s2 VARCHAR(MAX) = 'Jeff         Jones';
SELECT @s as BeforeString, dbo.RemoveMultipleSpaces(@s) AS AfterString
UNION
SELECT @s1 as BeforeString, dbo.RemoveMultipleSpaces(@s1) AS AfterString
UNION
SELECT @s2 as BeforeString, dbo.RemoveMultipleSpaces(@s2) AS AfterString

BeforeString              AfterString

Bob     Jones             Bob Jones
Jim Jones                 Jim Jones
Jeff         Jones        Jeff Jones

---

您可以编写一个用户定义的函数来压缩字符串中的空格，然后使用UDF来更新表。@哈波：很好的建议我在回答中添加了一个UDF定义：）