Question

I need to filter result sets from sql server based on selections from a multi-select list box. I’ve been through the idea of doing an instring to determine if the row value exists in the selected filter values, but that’s prone to partial matches (e.g. Car matches Carpet).

I also went through splitting the string into a table and joining/matching based on that, but I have reservations about how that is going to perform.

Seeing as this is a seemingly common task, I’m looking to the Stack Overflow community for some feedback and maybe a couple suggestions on the most commonly utilized approach to solving this problem.

Answer 1

I solved this one by writing a table-valued function (we’re using 2005) which takes a delimited string and returns a table. You can then join to that or use WHERE EXISTS or WHERE x IN. We haven’t done full stress testing yet, but with limited use and reasonably small sets of items I think that performance should be ok.

Below is one of the functions as a starting point for you. I also have one written to specifically accept a delimited list of INTs for ID values in lookup tables, etc.

Another possibility is to use LIKE with the delimiters to make sure that partial matches are ignore, but you can’t use indexes with that, so performance will be poor for any large table. For example:

SELECT      my_column FROM      My_Table WHERE      @my_string LIKE '%|' + my_column + '|%' 

.

/*     Name:       GetTableFromStringList     Description:    Returns a table of values extracted from a delimited list     Parameters:             @StringList - A delimited list of strings             @Delimiter - The delimiter used in the delimited list      History:     Date        Name            Comments     ----------  -------------   ----------------------------------------------------     2008-12-03  T. Hummel   Initial Creation */ CREATE FUNCTION dbo.GetTableFromStringList (     @StringList VARCHAR(1000),     @Delimiter  CHAR(1) = ',' ) RETURNS @Results TABLE (     String  VARCHAR(1000)   NOT NULL ) AS BEGIN     DECLARE         @string     VARCHAR(1000),         @position   SMALLINT      SET @StringList = LTRIM(RTRIM(@StringList)) + @Delimiter     SET @position = CHARINDEX(@Delimiter, @StringList)      WHILE (@position > 0)     BEGIN         SET @string = LTRIM(RTRIM(LEFT(@StringList, @position - 1)))          IF (@string <> '')         BEGIN             INSERT INTO @Results (String) VALUES (@string)         END          SET @StringList = RIGHT(@StringList, LEN(@StringList) - @position)         SET @position = CHARINDEX(@Delimiter, @StringList, 1)     END      RETURN END