DESCRIPTION

Supported is a limited set of SQL functions and operators.

FUNCTIONS

  ALTER TABLE table ADD [COLUMN] columndef
  CREATE TABLE table ( columndefs )
  DROP TABLE table
  SELECT columns FROM table
  SELECT columns FROM table WHERE condition
  DELETE FROM table
  DELETE FROM table WHERE condition
  INSERT INTO table values
  INSERT INTO table ( columns ) values
  UPDATE table SET assignments
  UPDATE table SET assignments WHERE condition

OPERATORS

  "="  : equal
  "<"  : smaller than
  "<=" : smaller/equal than
  ">"  : larger than
  ">=" : larger/equal than
  "<>" : not equal
  "~"  : Substring matching

NOTES

• SQL does not support '.' (dots) in table names.
• Supported table name characters are only:
  [A-Za-z][A-Za-z0-9_]*
• A table name must start with a character, not a number.
• Brackets are needed, e.g. for
  

        select * from some_table where (3*(some_field - another_field) > 5)
       

  The parser does not know about precedence yet, so the sub-clause has to be in brackets to avoid ambiguity.
• Text-string matching requires the text part to be 'single quoted' and multiple queries should be contained in "double quotes". e.g.
  

        d.vect map where="individual='juvenile' and area='beach'"
  	

• An error message such as "dbmi: Protocol error" either indicates an invalid column name or an unsupported column type (then the GRASS SQL parser needs to be extended).
• DBF column names are limited to 10 characters (DBF API definition)

EXAMPLES

 d.vect trapping_sites_points fcol=black icon=basic/diamond col=white size=13 \
    where="valley <> 'LAMAR' OR (valley = 'LAMAR' AND description = 'extensive trapping')"

Select all attributes from table where str1 column values are not 'No Name':

 echo "SELECT * FROM archsites WHERE str1 <> 'No Name'" | db.select

SEE ALSO

Last changed: $Date: 2005/05/10 09:58:07 $