Using SQL statements into TCR Cognos reports

Answer

Yes, you can put SQL statement directly into Cognos reports using the SQL operator available in the Insertable objects view from Cognos Report Studio.

Generally speaking, you would need to:

a) Click on Query Explorer.
b) from Insertable Objects, insert a Query
c) from Insertable Objects, insert SQL.
d) In the properties Select a Datasource.
e) double click the SQL and enter your SQL.

Consider that using this method you will miss a lot of advantages given by the features built into Cognos.

The best option remains using Framework Manager to improve the performance of the data model used by those reports.
Furthermore, using just hardcoded SQL queries makes it more difficult to maintain because you would have to open each report and manually apply the needed changes.
This option can be useful in case you want to make comparison test or to start exploring Cognos Report Studio features, but it should not be used every time.

For additional information about this option, please refer to the Cognos manual:

http://www-01.ibm.com/support/knowledgecenter/SSEP7J_8.4.0/com.ibm.swg.im.cognos.ug_cr_rptstd.8.4.1.doc/ug_cr_rptstd_i_cr_rptstd_wrkdat_working_with_sql_mdx_re.html%23cr_rptstd_wrkdat_working_with_sql_mdx_rel?lang=en