Returns the static SQL string associated with this local statement. A statement should include
a SQL statement for each variant that can reasonably be expected to be generated by a
framework, but does not need to include a variant for each theoretically possible variant. The
given SQL strings will be used as the keys in a java.util.Map for quick lookup. This
means that it will not match all possible variants of the statement, which is OK, as this is
only intended to cover auto-generated query strings from frameworks/tools.
