SQL Preconditions Help


I am new to Liquibase and working my way through its functionalies.
Please help me with the following issue:

Regarding the SQL preconditions, is there a way to add complex SQL\PLSQL queries to the preconditions line, like:
–precondition-sql-check expectedResult:100 CREATE OR REPLACE FUNCTION totalRecords () RETURNS integer AS total declare total integer; BEGIN SELECT count(*) into total FROM schemaname.persons; RETURN total; END; total LANGUAGE plpgsql; select totalRecords();

The above query is just an example, as I will probably have to add complex functions or PLSQL code blocks in the prereconditions.
Is this possible?

Thank you,