CASE (Contains) rather than equal statement

18

Is there a method to use contain rather than equal in case statement?

For example, I am checking a database table has an entry

lactulose, Lasix (furosemide), oxazepam, propranolol, rabeprazole, sertraline, 

Can I use

CASE When dbo.Table.Column = 'lactulose' Then 'BP Medication' ELSE '' END AS 'BP Medication'

This did not work.

Thanks in advance

This question is tagged with sql-server sql-server-2008

~ Asked on 2012-05-15 23:59:11

The Best Answer is


30

CASE WHEN ', ' + dbo.Table.Column +',' LIKE '%, lactulose,%' 
  THEN 'BP Medication' ELSE '' END AS [BP Medication]

The leading ', ' and trailing ',' are added so that you can handle the match regardless of where it is in the string (first entry, last entry, or anywhere in between).

That said, why are you storing data you want to search on as a comma-separated string? This violates all kinds of forms and best practices. You should consider normalizing your schema.

In addition: don't use 'single quotes' as identifier delimiters; this syntax is deprecated. Use [square brackets] (preferred) or "double quotes" if you must. See "string literals as column aliases" here: http://msdn.microsoft.com/en-us/library/bb510662%28SQL.100%29.aspx

EDIT If you have multiple values, you can do this (you can't short-hand this with the other CASE syntax variant or by using something like IN()):

CASE 
  WHEN ', ' + dbo.Table.Column +',' LIKE '%, lactulose,%' 
  WHEN ', ' + dbo.Table.Column +',' LIKE '%, amlodipine,%' 
  THEN 'BP Medication' ELSE '' END AS [BP Medication]

If you have more values, it might be worthwhile to use a split function, e.g.

USE tempdb;
GO

CREATE FUNCTION dbo.SplitStrings(@List NVARCHAR(MAX))
RETURNS TABLE
AS
   RETURN ( SELECT DISTINCT Item FROM
       ( SELECT Item = x.i.value('(./text())[1]', 'nvarchar(max)')
         FROM ( SELECT [XML] = CONVERT(XML, '<i>'
         + REPLACE(@List,',', '</i><i>') + '</i>').query('.')
           ) AS a CROSS APPLY [XML].nodes('i') AS x(i) ) AS y
       WHERE Item IS NOT NULL
   );
GO

CREATE TABLE dbo.[Table](ID INT, [Column] VARCHAR(255));
GO

INSERT dbo.[Table] VALUES
(1,'lactulose, Lasix (furosemide), oxazepam, propranolol, rabeprazole, sertraline,'),
(2,'lactulite, Lasix (furosemide), lactulose, propranolol, rabeprazole, sertraline,'),
(3,'lactulite, Lasix (furosemide), oxazepam, propranolol, rabeprazole, sertraline,'),
(4,'lactulite, Lasix (furosemide), lactulose, amlodipine, rabeprazole, sertraline,');

SELECT t.ID
  FROM dbo.[Table] AS t
  INNER JOIN dbo.SplitStrings('lactulose,amlodipine') AS s
  ON ', ' + t.[Column] + ',' LIKE '%, ' + s.Item + ',%'
  GROUP BY t.ID;
GO

Results:

ID
----
1
2
4

~ Answered on 2012-05-16 00:05:34


6

Pseudo code, something like:

CASE
  When CHARINDEX('lactulose', dbo.Table.Column) > 0 Then 'BP Medication'
ELSE ''
END AS 'Medication Type'

This does not care where the keyword is found in the list and avoids depending on formatting of spaces and commas.

~ Answered on 2012-05-16 00:19:05


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