On 23/09/10 5:13 PM, [email protected] wrote:
Message: 3
Date: Wed, 22 Sep 2010 16:51:08 -0400 (EDT)
From: PixelPusher<[email protected]>
Subject: [GRASS-user] Connecting GRASS to a MySQL database?
To:[email protected]
Message-ID:<[email protected]>
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=<ip address>,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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