Use "like" or an adverb. e.g.
q)select from tab where col2 like "testchararr"
col1 col2
---------------------
testsym "testchararr"
q)select from tab where col2~\:"testchararr"
col1 col2
---------------------
testsym "testchararr"
q)select from tab where col2 like "test"
col1 col2
---------
q)select from tab where col2~\:"test"
col1 col2
---------
I advise checking the speed of each method. For more examples of qsql like in use see: http://www.timestored.com/b/forums/topic/string-functions-like-search-replace-regex/