Name of table.
Either a dictionary or the value to be looked up.
Name of field to use as key (optional).
This method is the basic mechanism to get a single row. It
assumes that the key specifies a unique row. If
keyname is not specified then the primary key
for the table is used. If
arg is a
dictionary then the value for the key is taken from it and it is
modified to include the new values, replacing existing values
where necessary. The OID is also put into the dictionary but in
order to allow the caller to work with multiple tables, the
attribute name is munged to make it unique. It consists of the
string oid_ followed by the name of the