Local variable with multiple value list - sql

Question

I use Excel connection to connect to SQL Server to query data from SQL server to Excel.
I have below WHERE clause in the Excel connection couple times. I need to replace the WHERE multiple value list from time to time. To simply the replacement, I want to use a local parameter, #Trans. With the local parameter, I can change it only and all SQL will use it to query.
WHERE Type in ('R','D','C')
If it is single option, below code works.
DECLARE #TRans CHAR(200)= 'R';
SELECT .....
WHERE Type in (#Trans)
If it is multiple options, the below code does not works
DECLARE #TRans CHAR(200)= 'R,D,C';
SELECT .....
WHERE Type in (#Trans)
DECLARE #TRans CHAR(200)= '''R'''+','+'''D'''+','+'''C''';
SELECT .....
WHERE Type in (#Trans)
How to declare #Trans for multiple value list, for example ('R','D','C')? Thank you.

Answer 1

You can use dynamic sql
DECLARE #TRans VARCHAR(200)= '''R'',''D'',''C''';
DECLARE #sql VARCHAR(MAX) = '';
SET #sql = 'SELECT * FROM table WHERE Type in (' + #Trans + ');'
EXEC #sql
Take note of the quotes for the values in #TRans since these character values.
If you want to check the value of #sql which you will see the constructed sql statement, replace EXEC #sql with PRINT #sql.
Result of #sql
SELECT * FROM table WHERE Type in ('R','D','C');

Answer 2

As you can see by now, SQL Server does NOT support macro substition. This leaves a couple of options. One is to split the string.
If not 2016, here is a quick in-line approach which does not require a Table-Valued Function
Example
Declare #Trans varchar(max)='R,D,C' -- Notice no single quotes
Select ...
Where Type in (
Select RetVal = LTrim(RTrim(B.i.value('(./text())[1]', 'varchar(max)')))
From (Select x = Cast('<x>' + replace(#Trans,',','</x><x>')+'</x>' as xml).query('.')) as A
Cross Apply x.nodes('x') AS B(i)
)

Answer 3

You can create a table named LocalParameter and keep local variables there. You can only get datas by updating LocalParameter table without changing the queries.
CREATE TABLE LocalParameter (Trans VARCHAR(MAX))
INSERT INTO LocalParameter
VALUES
(
',R,'
)
With LIKE you can use it like this:
SELECT .....
WHERE (SELECT TOP 1 A.Trans FROM LocalParameter A) LIKE ',' + Type + ','
To change WHERE clause:
UPDATE LocalParameter
SET Trans = ',R,D,C,'
Queries:
SELECT .....
WHERE (SELECT TOP 1 A.Trans FROM LocalParameter A) LIKE ',' + Type + ','
Local variables are added to the beginning and end of the comma.

Answer 4

You can use a split method to split csv values as shown below
DECLARE #delimiter VARCHAR(10)=','
DECLARE #input_string VARCHAR(200)='R,D,C'
;WITH CTE AS
(
SELECT
SUBSTRING(#input_string,0,CHARINDEX(#delimiter,#input_string)) AS ExtractedString,
SUBSTRING(#input_string,CHARINDEX(#delimiter,#input_string) + 1,LEN(#input_string)) AS PartString
WHERE CHARINDEX(#delimiter,#input_string)>0
UNION ALL
SELECT
SUBSTRING(PartString,0,CHARINDEX(#delimiter,PartString)) AS ExtractedString,
SUBSTRING(PartString,CHARINDEX(#delimiter,PartString)+1,LEN(PartString)) AS PartString
FROM CTE WHERE CHARINDEX(#delimiter,PartString)>0
)
SELECT ExtractedString FROM CTE
UNION ALL
SELECT
CASE WHEN CHARINDEX(#delimiter,REVERSE(#input_string))>0
THEN REVERSE(SUBSTRING(REVERSE(#input_string),0,CHARINDEX(#delimiter,REVERSE(#input_string))))
ELSE #input_string END
OPTION (MAXRECURSION 0)
This split method doesnt have any loops so it will be fast. then you integrate this with your query as below mentioned
DECLARE #delimiter VARCHAR(10)=','
DECLARE #input_string VARCHAR(200)='R,D,C'
;WITH CTE AS
(
SELECT
SUBSTRING(#input_string,0,CHARINDEX(#delimiter,#input_string)) AS ExtractedString,
SUBSTRING(#input_string,CHARINDEX(#delimiter,#input_string) + 1,LEN(#input_string)) AS PartString
WHERE CHARINDEX(#delimiter,#input_string)>0
UNION ALL
SELECT
SUBSTRING(PartString,0,CHARINDEX(#delimiter,PartString)) AS ExtractedString,
SUBSTRING(PartString,CHARINDEX(#delimiter,PartString)+1,LEN(PartString)) AS PartString
FROM CTE WHERE CHARINDEX(#delimiter,PartString)>0
)
SELECT * FROM [YourTableName] WHERE Type IN
(SELECT ExtractedString FROM CTE
UNION ALL
SELECT
CASE WHEN CHARINDEX(#delimiter,REVERSE(#input_string))>0
THEN REVERSE(SUBSTRING(REVERSE(#input_string),0,CHARINDEX(#delimiter,REVERSE(#input_string))))
ELSE #input_string END
)OPTION (MAXRECURSION 0)

Answer 5

If possible add a new table and then join to it in all your queries:
CREATE TABLE SelectedType
(
[Type] CHAR(1) PRIMARY KEY
)
INSERT INTO SelectedType
VALUES ('R','D','C')
Then your queries become:
SELECT *
FROM MyTable MT
INNER JOIN SelectedType [ST]
ON ST.[Type] = MT.[Type]
If you need to add, update or delete types then update the rows in SelectedType table.
This has the benefit of using SET BASED queries, is easy to understand and easy to add, update or delete required types.