NAME:
   mysqlquery
 PURPOSE:
   Submit MySQL query and get response as vectors of data (like readcol).
 DESCRIPTION:
   Submit a simple SQL query to MySQL server, using the connection
   previously opened with openmysql.  Retrieve the result into
   a row of variables, much as readcol does.  Return dimensionality
   of result(s).
 CATEGORY:
   Database

 CALLING SEQUENCE:
   mysqlquery,lun,query,[varables...],[format='(a,f,...)']

 INPUTS:
    lun    - The logical unit of the pipe (opened by openmysql).
    query  - String (or array of strings) to send to pipe.

 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
    format  - Specify format of output variables (default is ascii).
    cmd     - Flag indicating this is a command, not a query so
                don't bother processing the output (but do report the
                number of rows affected/warnings? - not implimented).
    verbose - Flag turns on debugging output to standard out.

 OUTPUTS:
    variables - A list of variables to recieve columns of output.
                   Default type is ascii, but use the format keyword to
                   specify other data types.

 KEYWORD OUTPUT PARAMETERS:
    HEADS   - String to receive array of column heads.
    NGOOD   - Number of valid lines found that were read.

 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
   Requires an open connection to MySQL server (established by
   use of openmysql) as well as valid permissions for whatever
   query or command is to be executed.

 PROCEDURE:
 MODIFICATION HISTORY:
   2002-02-14 Will Grundy, adapted from earlier version called mysql.pro
   2002-02-27 WG changed behavior so 'NULL' becomes NaN instead of
                  making the line be ignored when it occurs in a numerical
                  field.
   2002-03-25 WG changed to split on tab instead of white space, so that
       strings with internal spaces (but not tabs) can be retrieved.
   2003/01/10, MWB, fixed multi-line query error.  Only one query per
                       call is allowed.
   2006/11/09, PLC, changed strsplit call to use /preserve_null flag
                     this means a field can now return an empty string.
                     The behavior for non-'a' type fields is not defined
                     in this case.
   2007/07/15, MWB, added NGOOD output keyword
   2010/03/11, MWB, change behavior so that if there is only one valid
                     line the result is returned as a scalar instead of
                     a one-element vector.

 BUGS/WISH LIST:
   Ought to verify connection to MySQL server.
   Does nothing helpful with SQL command results.
   Does nothing helpful to identify/report bad SQL syntax.