Programming Guide

dm_gen_change_select_order_by

Edits the ORDER BY clause in a SELECT statement for automatic SQL generation 

#include <tmusubs.h>
int dm_gen_change_select_order_by(char *arg, char *widget_name, int sort_ind, int flag);

arg
Reserved for future use.

widget_name
The name of the widget whose column_name property is referenced in the ORDER BY clause. If the name of the database column is entered, it is ignored.

sort_ind
Specifies whether the sort is ascending (DM_GEN_ASC_SORTED) or descending (DM_GEN_DESC_SORTED). If set to an invalid value, an error is generated.

flag
Specifies the type of change to make with one of the following constants:

DM_GEN_APPEND
Adds the specified information to the end of the ORDER BY clause. This produces the following statement: 
DBMS DECLARE cursor FOR SELECT select_list
 FROM tables ORDER BY existing_order_by_list,
 column_position sort_ind

DM_GEN_PREPEND
Adds the specified information to the beginning of the ORDER BY clause. This produces the following statement: 
DBMS DECLARE cursor FOR SELECT select_list
 FROM tables ORDER BY column_position sort_ind,
 existing_order_by_list

DM_GEN_REPLACE_ALL
The specified information replaces the previous ORDER BY clause. This produces the following statement: 
DBMS DECLARE cursor FOR SELECT select_list
 FROM tables ORDER BY column_position sort_ind

If flag is set to this value and widget_name is set to an empty string, the ORDER BY clause is removed. For example: 

x = dm_gen_change_select_order_by
  ("", "", "", DM_GEN_REPLACE_ALL)

Returns

Description

dm_gen_change_select_order_by lets you edit the ORDER BY clause built with the SQL generator. The structure for the SELECT statement, which is built by a call to dm_gen_sql_info (generally in the TM_SEL_GEN event), must already exist before this function is called. Note that this function must be called once for each change you wish to make.

By default, the SQL generator builds the ORDER BY clause from values of the table view's Sort Widgets (sort_widgets) property. For more information on how the SQL generator builds statements, refer to Chapter 33, "Using Automated SQL Generation," in Application Development Guide.

This function can be implemented as part of a transaction manager event function which processes the TM_SEL_BUILD_PERFORM event. If you are modifying the select processing for a server view, call dm_gen_change_select_order_by from an event function attached to the first parent table view in the server view.

To view a sample event function written in JPL, refer to the example in this section. For more information on writing transaction event functions, refer to Chapter 32, "Writing Transaction Event Functions," in Application Development Guide.

Example

# Appends the order by list for titles table.
	# The Function property is set to titles_orderby.
	
proc titles_orderby (event)
	
vars retval(5)
	
if (event == TM_SEL_BUILD_PERFORM)
	  {
	  retval = dm_gen_change_select_order_by \
	    ("", "film_minutes", DM_GEN_ASC_SORTED, DM_GEN_APPEND)
 
  if (retval != 0)
  return TM_FAILURE
  }

return TM_PROCEED

See Also

dm_gen_sql_info