insert/update/set_field expected behaviour is to cast empty string to 0 for numeric columns

Expected behaviour to get cross-db support is to automatically cast empty strings to 0 in the following functions:

• insert_record
• update_record
• set_field

Rationale: DBs are idiot:

• MSSQL allows empties on int fields and saves them as 0, but not in decimal fields no matter of the nullability of the field)
• Oracle allows empties on int fields and saves them as NULL and only in NOT NULL fields. Same for decimal fields.
• MySQL doesn't allow empties in int/decimal fields (strict mode). Error.
• PG doesn't allow empties in int/decimal fields). Error.

So I guess we only can move to the "perform casting" alternative. Is the only that will work cross-db. The other (not perform casting) won't work as far as MSSQL and Oracle sometimes accept those empty strings.