Question

让我先说我是一个品牌打击新的SQL开发人员。我研究了这个并且找不到答案。

我在SSMS 2012工作，我有一个单列表（axis1），其值如下：

axis1
296.90, 309.4
296.32, 309.81
296.90
300.11, 309.81, 311, 313.89, 314.00, 314.01, V61.8, V62.3

我需要将此列转换为多列，如下所示：

axis1    axis2    axis3  axis4
296.90   309.4    null   null
296.32   309.81   null   null
296.90   null     null   null
300.11   309.81   311    313.89...

到目前为止，我已经尝试过/考虑过了：

select case when charindex(',',Axis1,1)>0 
            then substring(Axis1,1,CHARINDEX(',',Axis1,1)-1)
            else Axis1
       end as Axis1
from tablex

适用于已知列值的数据，但此列中可能有0,1或20+个值。

有没有办法将一列中未知数量的逗号分隔值拆分为多个单值列？提前感谢大家的帮助！

Answer 1

我在创建这个答案时做了一个假设，就是你需要将它作为一个单独的存储过程。

第1步

创建data type以允许使用将表值参数（TVP）传递到存储过程。

use db_name
GO
create type axisTable as table 
    (
        axis1 varchar(max)
    )
GO

第2步

创建解析值的过程。

USE [db_name]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE PROCEDURE [dbo].[usp_util_parse_out_axis] 
    (
        @axis_tbl_prelim axisTable readonly
    )
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    declare @axis_tbl axisTable

    --since TVP's are readonly, moving the data in the TVP to a local variable
    --so that the update statement later on will work as expected
    insert into @axis_tbl
    select *
    from @axis_tbl_prelim

    declare @comma_cnt int
        , @i int 
        , @sql_dyn nvarchar(max)
        , @col_list nvarchar(max)

    --dropping the global temp table if it already exists
    if object_id('tempdb..##axis_unpvt') is not null
        drop table ##axis_unpvt

    create table ##axis_unpvt
        (
            axis_nbr varchar(25)
            , row_num int
            , axis_val varchar(max)
        )

    --getting the most commas
    set @comma_cnt = (select max(len(a.axis1) - len(replace(a.axis1, ',', '')))
                        from @axis_tbl as a)

    set @i = 1
    while @i <= @comma_cnt + 1
    begin --while loop

        --insert the data into the "unpivot" table one parsed value at a time (all rows) 
        insert into ##axis_unpvt
        select 'axis' +  cast(@i as varchar(3))
        , row_number() over (order by (select 100)) as row_num --making sure the data stays in the right row
        , case when charindex(',', a.axis1, 0) = 0 and len(a.axis1) = 0 then NULL
                when charindex(',', a.axis1, 0) = 0 and len(a.axis1) > 0 then a.axis1
                when charindex(',', a.axis1, 0) > 0 then replace(left(a.axis1, charindex(',', a.axis1, 0)), ',', '')
                else NULL
        end as axis1
        from @axis_tbl as a

        --getting rid of the value that was just inserted from the source table
        update a
        set a.axis1 = case when charindex(',', a.axis1, 0) = 0 and len(a.axis1) > 0 then NULL
                           when charindex(',', a.axis1, 0) > 0 then rtrim(ltrim(right(a.axis1, (len(a.axis1) - charindex(',', a.axis1, 0)))))
                           else NULL
                      end
        from @axis_tbl as a
        where 1=1
        and (charindex(',', a.axis1, 0) = 0 and len(a.axis1) > 0
             or charindex(',', a.axis1, 0) > 0) 

        --incrementing toward terminating condition
        set @i += 1

    end --while loop

    --getting list of what the columns will be after pivoting
    set @col_list = (select stuff((select distinct ', ' + axis_nbr
                            from ##axis_unpvt as a
                            for xml path ('')),1,1,''))

    --building the pivot statement
    set @sql_dyn = '
    select '
    + @col_list + 
    '
    from ##axis_unpvt as a
    pivot (max(a.axis_val)
            for a.axis_nbr in ('
                                + @col_list + 
                                ')) as p'

    --executing the pivot statement
    exec(@sql_dyn);

END

第3步

使用步骤1中创建的数据类型作为参数进行过程调用。

use db_name
go

declare @tvp as axisTable

insert into @tvp values ('296.90, 309.4')
insert into @tvp values ('296.32, 309.81')
insert into @tvp values ('296.90')
insert into @tvp values ('300.11, 309.81, 311, 313.89, 314.00, 314.01, V61.8, V62.3')

exec db_name.dbo.usp_util_parse_out_axis @tvp

您的示例的结果如下：

将1列内未知数量的逗号分隔的varchars转换为多列

1 个答案: