This class encapsulates a connection to an SQL server. It is a
generic interface on top of the DB server specific
implementations. That doesn't mean that there aren't plenty of
server specific characteristics that still shine through, though.
This class also serves as an interface guideline for the DB server
specific connection classes.
Untyped and typed mode
The query results are returned in different ways depending on the
query functions used: The ..typed_query functions select
typed mode, while the other query functions uses the older untyped
mode.
In untyped mode, all values except SQL NULL are returned as
strings in their display representation, and SQL NULL is returned
as zero.
In typed mode, values are returned in pike native form where it
works well. That means at least that SQL integer fields are
returned as pike integers, floats as floats, SQL NULL as
Val.null , and of course strings still as strings. The
representation of other SQL types depend on the capabilities of
the server specific backends. It's also possible that floats in
some cases are represented in other ways if too much precision is
lost in the conversion to pike floats.
Sql.Null()->encode_json()