Compare strings and Highlight mismatch wherever found in T-SQL - sql

Question

I have below Material table which contains data like this:
[PO Number] [Actual Material] [Ideal Material]
----------------------------------------------------
1000000 Milk-Sugar-tea Milk-Sugar-Coffee
1000001 Milk-Water Milk-Water-Ice-tea
I have the requirement where I need to compare two columns Actual Material and Ideal material and highlight the mismatch materials in SQL.
Mismatch would be
[PO Number] [Actual Material] [Ideal Material] [Mismatch]
----------------------------------------------------------------
1000000 Milk-Sugar-tea Milk-Sugar-Coffee tea-coffee
1000001 Milk-Water Milk-Water-Ice-tea Ice-tea
How to achieve this in a SQL query?

Answer 1

As many others have very sensibly suggested, your first port of call should be to restructure your database so you are actually storing normalised data against your PO Numbers.
That said, something we are dealt a rubbish hand and have to play the cards we get. To answer your question exactly as it is asked, you can do the following:
If you are not on SQL Server 2016 and therefore cannot use the built in string_split function, start by creating your own:
create function [dbo].[StringSplit]
(
#str nvarchar(4000) = ' ' -- String to split.
,#delimiter as nvarchar(1) = ',' -- Delimiting value to split on.
,#num as int = null -- Which value to return.
)
returns #results table(ItemNumber int, Item nvarchar(4000))
as
begin
declare #return nvarchar(4000);
-- Handle null #str values
select #str = case when len(isnull(#str,'')) = 0 then '' else #str end;
-- Start tally table with 10 rows.
with n(n) as (select n from (values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) n(n))
-- Select the same number of rows as characters in #str as incremental row numbers.
-- Cross joins increase exponentially to a max possible 10,000 rows to cover largest #str length.
,t(t) as (select top (select len(#str) a) row_number() over (order by (select null)) from n n1,n n2,n n3,n n4)
-- Return the position of every value that follows the specified delimiter.
,s(s) as (select 1 union all select t+1 from t where substring(#str,t,1) = #delimiter)
-- Return the start and length of every value, to use in the SUBSTRING function.
-- ISNULL/NULLIF combo handles the last value where there is no delimiter at the end of the string.
,l(s,l) as (select s,isnull(nullif(charindex(#delimiter,#str,s),0)-s,4000) from s)
insert into #results
select rn as ItemNumber
,Item
from(select row_number() over(order by s) as rn
,substring(#str,s,l) as item
from l
) a
where rn = #num
or #num is null;
return;
end
Using this function you can then create a set each for your Actual Material and Ideal Material columns, combine them to find the differences using a full join and then concatenate the results using stuff and for xml into one string value:
declare #t table(PONumber int, ActualMaterial nvarchar(50), IdealMaterial nvarchar(50));
insert into #t values (1000000,'Milk-Sugar-tea','Milk-Sugar-Coffee'),(1000001,'Milk-Water','Milk-Water-Ice-tea');
with a as
(
select t.PONumber
,a.Item
from #t t
outer apply dbo.StringSplit(t.ActualMaterial,'-',null) a
), i as
(
select t.PONumber
,i.Item
from #t t
outer apply dbo.StringSplit(t.IdealMaterial,'-',null) i
), m as
(
select isnull(a.PONumber,i.PONumber) as PONumber
,isnull(a.Item,i.Item) as Item
from a
full join i
on(a.PONumber = i.PONumber
and a.Item = i.Item
)
where a.Item is null
or i.Item is null
)
select t.PONumber
,t.ActualMaterial
,t.IdealMaterial
,stuff((select '-' + m.Item
from m
where t.PONumber = m.PONumber
order by m.Item
for xml path('')
)
,1,1,'') as Mismatch
from #t t
order by PONumber;
Output:
+----------+----------------+--------------------+------------+
| PONumber | ActualMaterial | IdealMaterial | Mismatch |
+----------+----------------+--------------------+------------+
| 1000000 | Milk-Sugar-tea | Milk-Sugar-Coffee | Coffee-tea |
| 1000001 | Milk-Water | Milk-Water-Ice-tea | Ice-tea |
+----------+----------------+--------------------+------------+

Answer 2

I use a table value functions for split actual-material an ideal-material values.
Split Function detail isALTER FUNCTION [dbo].[Split]
(
#String NVARCHAR(4000),
#Delimiter NCHAR(1)
)
RETURNS TABLE
AS
RETURN
(
WITH Split(stpos,endpos)
AS(
SELECT 0 AS stpos, CHARINDEX(#Delimiter,#String) AS endpos
UNION ALL
SELECT endpos+1, CHARINDEX(#Delimiter,#String,endpos+1)
FROM Split
WHERE endpos > 0
)
SELECT 'Id' = ROW_NUMBER() OVER (ORDER BY (SELECT 1)),
'Value' = LTRIM(SUBSTRING(#String,stpos,COALESCE(NULLIF(endpos,0),LEN(#String)+1)-stpos))
FROM Split
)
For result table is
declare #result table (
[PO Number] int , [Actual Material] varchar(100),[Ideal Material] varchar(100),Mismatch varchar(200)
)
And query for result table insert is :
;with CTE AS (
select distinct s.* ,x1.Value x1value,x2.Value x2value
from dbo.material s
outer apply (select *from Split(s.[Actual Material],'-')) x1
outer apply (select *from Split(s.[Ideal Material],'-')) x2
),
CTE2 AS (
SELECT distinct c.[PO Number],c.[Actual Material],c.[Ideal Material]
,case when not exists (select *from CTE c2 where c2.[PO Number] = c.[PO Number] and c2.x2value = c.x1value ) then c.x1value else '' end [ActualMismatch]
,case when not exists (select *from CTE c2 where c2.[PO Number] = c.[PO Number] and c2.x1value = c.x2value ) then c.x2value else '' end [IdealMismatch]
FROM CTE c
)
insert into #result
SELECt c.[PO Number],c.[Actual Material],c.[Ideal Material],c.ActualMismatch Mismatch from CTE2 c
union
SELECt c.[PO Number],c.[Actual Material],c.[Ideal Material] ,c.IdealMismatch Mismatch from CTE2 c
where
(c.ActualMismatch !='' or
c.[IdealMismatch] !='')
order by 1
select [PO Number],[Actual Material],[Ideal Material],
STUFF((
SELECT '-' + mismatch
FROM #result
WHERE ([PO Number] = c.[PO Number])
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,1,2,'') AS mismatch
from #result c
where Mismatch !=''
Group by [PO Number],[Actual Material],[Ideal Material]
how to coalesce mismatch values ! => with xml stuff