MySQL 5.7 does not support CTE's. Refactor the table column metadata
query to avoid the CTE.

generator: support MySQL 5.7

…ses.

…ncy.

In parameterized statements integer literals, like Int(num), are replaced with a placeholders. For some expressions,
postgres interpreter will not have enough information to deduce the type. If this is the case postgres returns an error.
Int8, Int16, Int32.... functions now will add automatic type cast over a placeholder, so type deduction is always possible.

Add ability to exclude list of columns from ProjectionList.