int SPI_execute_with_args(const char *command,
                          int nargs, Oid *argtypes,
                          Datum *values, const char *nulls,
                          bool read_only, long count)   SPI_execute_with_args executes a command that might
   include references to externally supplied parameters.  The command text
   refers to a parameter as $n, and
   the call specifies data types and values for each such symbol.
   read_only and count have
   the same interpretation as in SPI_execute.
  
   The main advantage of this routine compared to
   SPI_execute is that data values can be inserted
   into the command without tedious quoting/escaping, and thus with much
   less risk of SQL-injection attacks.
  
   Similar results can be achieved with SPI_prepare followed by
   SPI_execute_plan; however, when using this function
   the query plan is always customized to the specific parameter values
   provided.
   For one-time query execution, this function should be preferred.
   If the same command is to be executed with many different parameters,
   either method might be faster, depending on the cost of re-planning
   versus the benefit of custom plans.
  
command string
number of input parameters ($1, $2, etc.)
an array of length nargs, containing the OIDs of the data types of the parameters
an array of length nargs, containing the actual parameter values
an array of length nargs, describing which parameters are null
      If nulls is NULL then
      SPI_execute_with_args assumes that no parameters
      are null.  Otherwise, each entry of the nulls
      array should be ' ' if the corresponding parameter
      value is non-null, or 'n' if the corresponding parameter
      value is null.  (In the latter case, the actual value in the
      corresponding values entry doesn't matter.)  Note
      that nulls is not a text string, just an array:
      it does not need a '\0' terminator.
     
true for read-only execution
maximum number of rows to return, or 0 for no limit