V9 Mapped Tables

[KathyB]

Has anyone successfully used XBASIC code to create a mapped table?

[Keith Hubert]

Re: V9 Mapped Tables

Hi Kathy,

What is a mapped table as against any other type of table?

[Bill Griffin]

Re: V9 Mapped Tables

Kieth,

Go to What's new in V9 (under help) and choose Mapped Tables for a very good explanation of what they are.

Bill

[Keith Hubert]

Re: V9 Mapped Tables

Thanks Bill, I'm sure going to find that useful.

Now how can we help Kathy?

[Bill Griffin]

Re: V9 Mapped Tables

We?? Well since there is no documentation regarding Mapped tables, I would just be guessing and probably wasting my time and Kathy's time. But if I had to do something like this I would look at the Tables functions and methods for sets and try replacing "set" with "mapped" and see if that worked. ie <tbl>.mapped_create()

Or just be patient and wait for someone who has done this already to help out.

[KathyB]

Re: V9 Mapped Tables

Thanks for your willingness to help - maybe someone out there has done this successfully or maybe someone from Alpha will provide some documentation.

[Bill Griffin]

Re: V9 Mapped Tables

Is there a particular reason you need to do this via xbasic?

[KathyB]

Re: V9 Mapped Tables

Yes, there are practical reasons for wanting to create a mapped table using XBASIC, and they are pretty much the same reasons that any developer might want to create a table or a set within written code - for reuseability and portabilty.

[Selwyn Rabins]

Re: V9 Mapped Tables

Has anyone successfully used XBASIC code to create a mapped table?

It can be done, but it is not documented because we intended mapped tables to be created through the User Interface. But behind the scenes, obviously, a5 is using xbasic to create the mapped table.

Here is how you can do it yourself (using the same 'for internal use only' functions that a5 uses).

1. The mapped table is created using this function

L a5_MappedTableCreate(C filename ,P def [,L flagAddTabletoDB ])

flagAddTableToDB is .t. or .f. and it controls whether the mapped table is added to the database.

filename is the fully qualified filename of the .dbf file.

def is a dot variable with a bunch of properties. this is the hard part.

if you create mapped table using the UI, you can then right click on the mapped table and select Mapped Tables, Show mapped table definition.

This will bring up a dialog that show the properties of the def.

You will see that 'def' has these properties:

alias - alias of the parent table in the map.
mapping - this is where the map between the physical fields and the mapped table fields are defined
relations - blank if the mapped table does not join tables. otherwise this is where the relationship between the physical tables is defined.
top - the relative filename of the parent table in the map.


play around with different map table definitions and examine the properties to get a feel for how the properties need to be specified.

the map table definition is actually stored in a text file with the same name as the table, but with a .dbp extension.

you can use this xbasic to examine the properties (from interactive window)

fn = table.filename_get("maptablename")
fn_dbp = file.filename_parse(fn,"dpn") + ".dbp"
txt = get_from_file(fn_dbp)
dim def as p 
property_from_string(def,txt)

?def.mapping

[Davidk]

Re: V9 Mapped Tables

So.... from what I read... Mapped Tables are kinda the same as Access Queries... does that sound right? Based on a single real table or multiple real tables with a relationship defined... plus calculated columns... and can be used like a table or a set.

David

[KathyB]

Re: V9 Mapped Tables

Fantastic! Thanks Selwyn.

[NoeticCC]

Re: V9 Mapped Tables

So.... from what I read... Mapped Tables are kinda the same as Access Queries... does that sound right?

Or like views in SQL databases :)