PASSING LISTS AS PARAMETERS TO STORED PROCEDURES IN SQL SERVER

Passing Lists as Parameters to Stored Procedures in SQL Server

There is no good way to do this in SQL Server. Someday they will have an array datatype like PostgreSQL.

In SQL Server 2005 and higher, this can be done using XML, but I don’t particularly see the need for the overhead. Use the function below to split a delimited string and select from the returned table. Its also very helpful for reporting.

CREATE FUNCTION [dbo].[SplitList] (@list VARCHAR(MAX), @separator VARCHAR(MAX) = ';')
RETURNS @table TABLE (Value VARCHAR(MAX))
AS BEGIN
  DECLARE @position INT, @previous INT
  SET @list = @list + @separator
  SET @previous = 1
  SET @position = CHARINDEX(@separator, @list)
  WHILE @position > 0 
  BEGIN
    IF @position - @previous > 0
      INSERT INTO @table VALUES (SUBSTRING(@list, @previous, @position - @previous))
    IF @position >= LEN(@list) BREAK
      SET @previous = @position + 1
      SET @position = CHARINDEX(@separator, @list, @previous)
  END
  RETURN
END

To use this function, simply pass your list, and specify the desired delimiter:

SELECT * FROM dbo.SplitList('1,2,3,4,5', ',')

This comes in handy when trying to report on, say, all unique customer emails who purchased a subset of SKUs in the past two days:

DECLARE @tbl TABLE (id VARCHAR(7));
INSERT @tbl SELECT * FROM dbo.SplitList('SKU1234,SKU2345,SKU3456,SKU4567', ',');

SELECT DISTINCT(LTRIM(RTRIM(c.email)))
FROM CMS o
INNER JOIN ITEMS i ON (o.ORDERNO = i.ORDERNO)
INNER JOIN CUST c ON (c.CUSTNUM = o.CUSTNUM)
WHERE i.ITEM IN (SELECT id FROM @tbl)
AND o.ODR_DATE >= DATEADD(day,-2,GETDATE())
AND LEN(c.email) > 0
AND c.email IS NOT NULL
AND c.email NOT LIKE '%@example.com'

Why use this technique? Performance. You make one call to the database. For the detractors of this design pattern, I ask: why would it be a bad idea to pass a collection to a stored procedure? Is it a bad idea in .NET to pass a collection as an argument to a method?


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