USE tempdb;
GO
CREATE TABLE myTable(I INT,C VARCHAR(4000));
GO
INSERT INTO myTable(I,C) VALUES (1,'abcd');
INSERT INTO myTable (I,C) VALUES (1,'12345');
GO
DECLARE @check_letter VARCHAR(128);
SET @check_letter='%[qwertyuiopasdfghjklzxcvbnm]%';

SELECT * FROM myTable
WHERE PATINDEX(@check_letter,C)=1;

Output:

I  C
-- ------------
1  abcd

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Cristian Andrei Lefter, SQL Server MVP
MCT, MCSA, MCDBA, MCAD, MCSD .NET,
MCTS, MCITP - Database Administrator SQL Server 2005
http://sqlserver.ro