var mismatch error during database lookup

ERROR: operator does not exist: character = bigint Hint: No operator matches the given name and argument type(s). You might need to add explicit type casts. Position: 63

Fields used - Single Select++ and Database Lookup++
populated single select with row a from database
lookup using single select field from database row b

Have tried type cast but did not correct issue.
here is the sql query used against postgreSQL v9 database -

SELECT short_name
FROM department_short_names
WHERE long_name = {customfield_11449}