I just searched all day almost on it. And maybe it can be some help to someone.
I wonder if this is a bug in FPC.
It was some notice on the same thing with delphi some years ago. They added the Double Precision in the 2009 version i think i remember.
Zeos components seems to use the default field types from FPC, when it's used the normal simple way.
I encountered a problem when i was going to get info on field types from a TZQuery.
I have Double Precision field types in the table, but it only show it as a float type.
I checked in Lazarus source\packages\fcl-db\src\
It does not have any Double Precision type. It only have the ftFloat type. And it is this type it gives when getting field type from the table.
So, i wondered what i could do.
I looked at ZDbcIntfs for Zeos, and see it has Double Precision.
So, i could not use TZQuery with the Open commend, and had to get the resultset with DbcStatement instead.
I then had to use stResult.GetMetadata.GetColumnType(i) for getting the correct field type.
I now get all the correct field types.
But this took a long time to figure out.
BTW
I wish i could buy a beer to every one that is working on Lazarus and FPC. You just do one amazing job.