使用CROSS APPLY的一栏以上 [英] Using CROSS APPLY for more than one column

问题描述

使用SQL Server的第3天.

Day #3 with SQL Server.

我正在尝试将2列定界数据合并为一个表值函数的一个输出.这是我的数据:

I am trying to combine 2 columns of delimited data into one output from a Table Valued Function. Here is my data:

我希望以以下格式处理数据并将其放入表格中:

I would like the data to be processed and placed into a table in the following format:

我目前正在尝试使用此CROSS APPLY TSQL语句，但是我不知道自己在做什么.

I am currently trying to use this CROSS APPLY TSQL statement, but I don't know what I'm doing.

USE [Metrics]
INSERT INTO dbo.tblSplitData(SplitKey, SplitString, SplitValues)
SELECT d.RawKey, c.*, e.*
FROM dbo.tblRawData d
CROSS APPLY dbo.splitstringcomma(d.DelimitedString) c, dbo.splitstringcomma(d.DelimitedValues) e

我对CROSS APPLY的研究具有广泛的背景，我不了解在这种情况下应如何应用它.我是否需要一个带有附加CROSS APPLY的子查询和一个联接来组合两个表值函数的返回值的子查询?

My research on CROSS APPLY has broad context, and I don't understand how it should be applied in this scenario. Do I need a subquery with an additional CROSS APPLY and a join to combine the returns from the two Table Valued Functions?

这是我最初使用的拆分功能(我不记得作者将其归功于这些功能):

Here is the split function I was using originally (I can't remember the author to credit them):

CREATE FUNCTION [dbo].[splitstring] ( @stringToSplit VARCHAR(MAX), @Delimiter CHAR(1))
RETURNS
 @returnList TABLE ([Name] [nvarchar] (500))
AS
BEGIN

 DECLARE @name NVARCHAR(255)
 DECLARE @pos INT

 WHILE CHARINDEX(@Delimiter, @stringToSplit) > 0
 BEGIN
  SELECT @pos  = CHARINDEX(@Delimiter, @stringToSplit)  
  SELECT @name = SUBSTRING(@stringToSplit, 1, @pos-1)

  INSERT INTO @returnList 
  SELECT @name

  SELECT @stringToSplit = SUBSTRING(@stringToSplit, @pos+1, LEN(@stringToSplit)-@pos)
 END

 INSERT INTO @returnList
 SELECT @stringToSplit

 RETURN
END

修改并编辑修改后的查询

USE [Metrics] 
INSERT INTO dbo.tblSplitData(SplitKey, SplitString, SplitValues)
SELECT s.RawKey, s.SplitString, v.SplitValues
FROM (
SELECT d.RawKey, d.DelimitedString,
 c.item SplitString, c.rn
FROM dbo.tblRawData d
CROSS APPLY dbo.splitstring(d.DelimitedString, ',') c
) s

INNER JOIN

(
SELECT d.RawKey, d.DelimitedValues,
 c.item SplitValues, c.rn
FROM dbo.tblRawData d
CROSS APPLY dbo.splitstring(d.DelimitedValues, ',') c
) v
on s.RawKey = v.RawKey
and s.rn = v.rn;

推荐答案

如果我们可以看到您的分割字符串函数，则回答这个问题可能会更容易.我的答案是使用我拥有的拆分功能的版本.

It might be easier to answer this if we could see your split string function. My answer is using a version of my split function that I have.

我将在您的拆分函数中包含一个行号，您可以使用该行号来联接拆分字符串和拆分值.

I would include in your split function a row number that you can use to JOIN the split string and the split values.

分割功能:

CREATE FUNCTION [dbo].[Split](@String varchar(MAX), @Delimiter char(1))       
returns @temptable TABLE (items varchar(MAX), rn int)       
as       
begin      
    declare @idx int       
    declare @slice varchar(8000)   
    declare @rn int = 1 -- row number that increments with each value in the delimited string

    select @idx = 1       
        if len(@String)<1 or @String is null  return       

    while @idx!= 0       
    begin       
        set @idx = charindex(@Delimiter,@String)       
        if @idx!=0       
            set @slice = left(@String,@idx - 1)   
        else       
            set @slice = @String       

        if(len(@slice)>0)  
            insert into @temptable(Items, rn) values(@slice, @rn)       

        set @String = right(@String,len(@String) - @idx)       
        set @rn = @rn +1

        if len(@String) = 0 break       
    end   
return 
end;

然后，如果要拆分多个列，则可以使用类似于以下内容的查询:

Then if you have multiple columns to split, you could use a query similar to the following:

INSERT INTO dbo.tblSplitData(SplitKey, SplitString, SplitValues)
select s.rawkey,
  s.splitstring,
  v.splitvalues
from
(
  SELECT d.RawKey, d.delimitedstring, d.delimitedvalues, 
    c.items SplitString, 
    c.rn
  FROM dbo.tblRawData d
  CROSS APPLY dbo.Split(d.DelimitedString, ',') c
) s
inner join
(
  SELECT d.RawKey, d.delimitedstring, d.delimitedvalues, 
    c.items SplitValues, 
    c.rn
  FROM dbo.tblRawData d
  CROSS APPLY dbo.Split(d.DelimitedValues, ',') c
) v
  on s.rawkey = v.rawkey
  and s.delimitedstring = v.delimitedstring
  and s.rn = v.rn;

请参见带有演示的SQL小提琴

这使用两个子查询来生成拆分值列表，然后使用拆分函数创建的行号将它们连接起来.

This uses two subqueries that generate the list of split values, then they are joined using the row number created by the split function.

这篇关于使用CROSS APPLY的一栏以上的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！