Richard,
Yeah... Merge might not be the right word. I'm importing a lot of files downloaded from the USGS site, for example, state boundaries. There are 6 separate files, but I want them all to go into the same database table/map layer. The import vector function always wants to put each import into its own table/layer.

Thom

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-----Original message-----
From: Richard Chirgwin <[email protected]>
To: Thom DeCarlo <[email protected]>
Cc: [email protected]
Sent: 2010 Sep, Fri, 24 21:46:26 GMT+00:00
Subject: Re: [GRASS-user] Connecting GRASS to a MySQL database?

 It depends on what you mean by "merge".

v.patch is the "official" tool to merge two vectors, but you could use v.overlay (option=or).

Richard

On 24/09/10 10:56 PM, Thom DeCarlo wrote:
Richard,
Thanks! That was exactly the information I needed.

Now to figure out how to merge layers...

Thom

/Sent via DROID on Verizon Wireless/


-----Original message-----

    *From: *Richard Chirgwin <[email protected]>*
    To: *[email protected]*
    Sent: *2010 Sep, Thu, 23 07:20:51 GMT+00:00*
    Subject: *Re: [GRASS-user] Connecting GRASS to a MySQL database?

    On 23/09/10 5:13 PM, [email protected] wrote:
    > Message: 3
    > Date: Wed, 22 Sep 2010 16:51:08 -0400 (EDT)
    > From: PixelPusher
    > Subject: [GRASS-user] Connecting GRASS to a MySQL database?
    > To:[email protected]
    > Message-ID:
    > Content-Type: text/plain; charset=UTF-8; format=flowed; delsp=no
    >
    > Sorry for the n00bish question, but I'm confused by the GRASS
    on-line
    > docs.
    >
    > I have a MySQL database running on my local computer. Let's say
    that the
    > MySQL user name is TRD and he has access to a database called
    TRD where
    > I want to store my StateBoundaries table.
    >
    > I can start the GRASS (6.4.0) Python interface and select
    > "Database->Manage Databases->Connect" from the pulldown menu. I
    am then
    > faced with the choice of driver, where I select "mysql". But,
    then it
    > needs the Database name. This is where I get lost. The string in the
    > text field says, "$GISDBASE/$LOCATION_NAME/$MAPSET/TRD". I'm not
    sure
    > where GRASS is getting the values that substitute for those
    things that
    > look like script variables. I guess the "$LOCATION_NAME" and
    "$MAPSET"
    > come from the location and mapset that I selected when GRASS
    started.
    > But, where is "$GISDBASE" set?
    >
    > I also step through the log in process by setting the
    appropriate user
    > name and password. I know that I can use this combination to
    access the
    > MySQL database through its command line interface.
    >
    > The next thing I do is try to test the connection. However, this
    results
    > in lots of errors like, "Cannot connect to MySQL, Access denied for
    > user" and "ERROR: Unable to open database
    > <$GISDBASE/$LOCATION_NAME/$MAPSET/TRD>". It looks like GRASS is not
    > using the right username and password and not doing the variable
    > substitution that I was expecting.
    >
    > Can anoyone give me some hints on how to get this thing started?
    >
    > Thanks!
    > Thom
    Thom,

    Having taught a few people how to use Grass-GIS, I can say that
    database parameters confuse a great many of them!

    The parameters you see are for the default dbf driver (Grass-GIS
    uses this driver as the default for any new mapset). For MySQL,
    you provide the database location, and also login.

    So where you see the $GISDBASE/$LOCATION_NAME/$MAPSET/dbf/ string,
    you want:
    database=host=,dbname=TRD

    But you'll also have to login. Eg (command line):

    db.login user=TRD password="somepassword"

    (the inverted commas are needed at the command line but not using
    the GUI)

    Notes:

    1. From now on, every map you make in this particular mapset will
    use the MySQL database as its default connection. Don't try to mix
    different database drivers within a mapset - you'll get a headache!

    2. Database parameters are stored only within the mapset you're
    using. If you want to connect a different mapset to MySQL, you
    have to set its connection.

    Richard Chirgwin
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