TSQL stuff for xml path and sub query - sql-server

Question

I've to replace csv datas in column by correspondant id always in csv format
I've a problem with this query :
select t0.code , t0.categories, t0.departement, (
SELECT Stuff((
SELECT N', ' + CONVERT(varchar, id_categorie) FROM tcategories t1 WHERE t0.departement = t1.departement COLLATE French_CI_AI and categorie IN (t0.tcategories)
FOR XML PATH(''),TYPE).value('text()[1]','varchar(max)'),1,1,N'')) as id_colonne
FROM #codes_reductions t0 where categories is not null
Here is the result :
code | categories | departement | id_colonne
AIRSTREAM | 'A','B','BA' | JMQ | NULL
If I replace 'and categorie IN (t0.tcategories)' by and categorie IN ('A','B','BA') the query works good
Here is the result :
code | categories | departement | id_colonne
AIRSTREAM | 'A','B','BA' | JMQ | 128, 129, 260
I tryed to use COLLATE French_CI_AI on my column, but without success. Any idea ?

Answer 1

... categorie IN (t0.tcategories) ....
The cause of your problem is that categorie column stores those values ('A','B','BA') as a single value not as an array / list / table of values. So, SQL Server compares two strings thus s1 IN (s2) which is equivalent to s1 = s2 => A IN ('A','B','BA') <=> A = 'A','B','BA'.
Example (note: double single quotes ('') are used to define an empty string while four single quotes ('''') are used to define a string with a single quote: SELECT '''' --> '):
DECLARE #categories VARCHAR(1000);
SET #categories = '''A'',''B'',''BA'''
SELECT #categories AS ColA, CASE WHEN 'A' IN (#categories) THEN 'TRUE' ELSE 'FALSE' END AS Col2
/*
ColA Col2
------------ -----
'A','B','BA' FALSE
*/
The solution on short term is to use one of following conditions:
C#1 (if categorie contains single quotes): ... t0.tcategories LIKE '%' + categorie + '%' ....
C#2 (when categorie doesn't contains single quotes): ... t0.tcategories LIKE '%''' + categorie + '''%' ....
Example:
DECLARE #categories VARCHAR(1000);
SET #categories = '''A'',''B'',''BA'''
SELECT #categories AS ColA, CASE WHEN #categories LIKE '%''A''%' THEN 'TRUE' ELSE 'FALSE' END AS Col2
/*
ColA Col2
------------ -----
'A','B','BA' TRUE
*/
Second note: this works when every separate value from t0.tcategories column doesn't includes single quote(s) (example: 'B'A' / 'B''A' ).
On medium/long term, you should store separately every single value from tReduction.tCategories column using another table :
CREATE TABLE dbo.ReductionCategory (
... pk ...,
ReductionCode INT NOT NULL REFERENCES dbo.tReduction(ReductionCode), -- FK
CategoryCode INT NOT NULL REFERENCES dbo.tCategories(CategoryCode) -- FK
)
Thus, condition becomes
... categorie /*CategoryCode*/
IN (
SELECT rc.CategoryCode FROM dbo.ReductionCategory rc
WHERE rc.ReductionCode = t0.ReductionCode
) ....