MySQL DATABASE DRIVER

       MySQL database driver enables GRASS to store vector attributes in MySQL server.

       Because  vector  attribute  tables are created automatically when a new vector is written and the name of
       the table is the same as the name of the vector it is good practice to create a  new  database  for  each
       GRASS mapset.

Creating a MySQL database

       A new database is created within MySQL:
       mysql> CREATE DATABASE mydb;
       See the MySQL manual for details.

Driver and database name

       GRASS  modules  require  2  parameters  to  connect  to  a  database.   Those parameters are ’driver’ and
       ’database’. For MySQL driver the parameter ’driver’ should  be  set  to  value  ’mysql’.   The  parameter
       ’database’ can be given in two formats:

           •   Database name - in case of connection from localhost

           •   String of comma separated list of kye=value options.  Supported options are:

               •   dbname - database name

               •   host - host name or IP address

               •   port - server port number
       Examples of connection parameters:
         db.connect driver=mysql database=mytest
         db.connect driver=mysql database=’dbname=mytest,host=test.grass.org’

Data types

       GRASS supports almost all MySQL data types with following limitations:

           •   Binary  columns  (BINARY, VARBINARY, TINYBLOB, MEDIUMBLOB, BLOB, LONGBLOB) are not not supported.
               If a table with binary column(s) is used in GRASS a warning is printed  and  only  the  supported
               columns are returned in query results.

           •   Columns of type SET and ENUM are represented as string (VARCHAR).

           •   Very  large  integers  in  columns of type BIGINT can be lost or corrupted because GRASS does not
               support 64 bin integeres on most platforms.

           •   GRASS does not currently distinguish types TIMESTAMP  and  DATETIME.  Both  types  are  in  GRASS
               interpreted as TIMESTAMP.

Indexes

       GRASS  modules  automatically  create  index  on  key column of vector attributes table. The index on key
       column is important for performance of modules which update the attribute  table,  for  example  v.to.db,
       v.distance and v.what.rast.

Privileges

       Because  MySQL  does  not  support  groups of users and because only MySQL ’root’ can grant privileges to
       other users GRASS cannot automatically grant select privileges on created tables to group of users.

       If you want to give privilege to read data from your mapset to other users you have  to  ask  your  MySQL
       server  administrator  to  grant select privilege to them on the MySQL database used for that mapset. For
       example, to allow  everybody to read data in from your database ’mydb’:
       shell> mysql --user=root mysql
       mysql> GRANT SELECT ON mydb.* TO ’’@’%’;

Schemas

       Because MySQL does not support database schemas the parameter ’schema’ of module db.connect should  never
       be  set  to  any  value. If you set that parameter for MySQL driver GRASS will try to write tables to the
       specified schema which will result in errors.

Groups

       MySQL does not support user groups. Any settings specified by ’group’ parameter of module db.connect  are
       ignored by GRASS for MySQL driver.

Troubleshooting: SQL syntax error

       Attempting  to  use  a reserved SQL word as column or table name will result in a "SQL syntax" error. The
       list of reserved words for MySQL can be found in the MySQL manual.

SEE ALSO

        db.connect, SQL support in GRASS GIS

Credits

       Development of the driver was sponsored by Faunalia (Italy) as part of a project for ATAC.

AUTHOR

       Radim Blazek

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual