拆分sql server中的字符串

Question

我在数据库中有一个逗号分隔的字符串。像'apple,banana,pineapple,grapes'我需要在逗号的基础上拆分这个字符串并遍历这个。因为在sql server中没有内置函数，是有任何有效的方法可以实现这一目标。

Answer 1

Try this function

CREATE FUNCTION [dbo].[func_Split] 
    (   
    @DelimitedString    varchar(8000),
    @Delimiter              varchar(100) 
    )
RETURNS @tblArray TABLE
    (
    ElementID   int IDENTITY(1,1),  -- Array index
    Element     varchar(1000)               -- Array element contents
    )
AS
BEGIN

    -- Local Variable Declarations
    -- ---------------------------
    DECLARE @Index      smallint,
                    @Start      smallint,
                    @DelSize    smallint

    SET @DelSize = LEN(@Delimiter)

    -- Loop through source string and add elements to destination table array
    -- ----------------------------------------------------------------------
    WHILE LEN(@DelimitedString) > 0
    BEGIN

        SET @Index = CHARINDEX(@Delimiter, @DelimitedString)

        IF @Index = 0
            BEGIN

                INSERT INTO
                    @tblArray 
                    (Element)
                VALUES
                    (LTRIM(RTRIM(@DelimitedString)))

                BREAK
            END
        ELSE
            BEGIN

                INSERT INTO
                    @tblArray 
                    (Element)
                VALUES
                    (LTRIM(RTRIM(SUBSTRING(@DelimitedString, 1,@Index - 1))))

                SET @Start = @Index + @DelSize
                SET @DelimitedString = SUBSTRING(@DelimitedString, @Start , LEN(@DelimitedString) - @Start + 1)

            END
    END

    RETURN
END

Example Usage – simply pass the function the comma delimited string as well as your required delimiter.

DECLARE @SQLStr varchar(100)
SELECT @SQLStr = 'Mickey Mouse, Goofy, Donald Duck, Pluto, Minnie Mouse'

SELECT
    *
FROM
    dbo.func_split(@SQLStr, ',')

Result will be like this

Answer 2

... Since there is no built in function in sql server ...

That was true at the time you asked this question but SQL Server 2016 introduces STRING_SPLIT .

So you can just use

SELECT value
FROM   STRING_SPLIT ('apple,banana,pineapple,grapes', ',') 

There are some limitations (only single character delimiters accepted and a lack of any column indicating the split index being the most eye catching). The various restrictions and some promising results of performance testing are in this blog post by Aaron Bertrand .

Answer 3

You can convert your data to XML, by replacing the comma by a custom tag, in this case, <w> for word.

create table t(col varchar(255));
insert into t values ('apple,banana,pineapple,grapes');
insert into t values ('car,bike,airplane');

select cast(('<w>' + replace(col, ',', '</w><w>') + '</w>') as xml) as xmlValue
  from t

Which returns

|                                               XMLVALUE |
|--------------------------------------------------------|
| <w>apple</w><w>banana</w><w>pineapple</w><w>grapes</w> |
|                   <w>car</w><w>bike</w><w>airplane</w> |

Now, if you use this query as a inner xml select, the outer query can split it into distinct rows:

Solution:

select split.xmlTable.value('.', 'varchar(255)') as xmlValue
from (

   select cast(('<w>' + replace(col, ',', '</w><w>') + '</w>') as xml) as xmlValue
     from t

) as xmlTable
cross apply xmlValue.nodes ('/w') as split(xmlTable);

Live sqlFiddle

Answer 4

I have a solution using Recursion as follows

Create function split_string(@str as nvarchar(max),@separator as char(1)) returns @myvalues Table (id int identity(1,1),myval nvarchar(100))
as 
--Kamel Gazzah
--23/04/2019
begin
with cte as(
select @str [mystr],
cast(1 as int) [Start],
charindex(@separator,@str)as Nd
union all
select substring(@str,nd+1,len(@str)),cast(Nd+1 as int),charindex(@separator,@str,Nd+1) from cte
where nd>0
)
insert into @myvalues(myval) 
select case when nd>0 then substring(@str,start,Nd-start) 
else substring(@str,start,len(@str)) end [splitted] 
from cte   OPTION (MAXRECURSION 1000);
return ;
end;

You can call this function

select * from split_string('apple,banana,pineapple,grapes',',')