Programming Guide

dm_gen_change_select_list

Edits the select list for automatic SQL generation 

#include <tmusubs.h>
int dm_gen_change_select_list(char *arg, char *sel_expr, char *prolfx_alias, int flag);

arg
Reserved for future use.

sel_expr
The select expression. If the expression is invalid, the engine returns an error.

prolfx_alias
Name of the Panther variable to use in the DBMS ALIAS statement. This variable should not be a local JPL variable. If this variable does not exist or is blank, the SELECT statement fetches the expression's values, but they are ignored. This is not considered an error.

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

DM_GEN_APPEND
Adds sel_expr to the end of the select list. prolfx_alias is added after the existing aliases. This produces the following statements: 
DBMS DECLARE cursor FOR SELECT existing_select_list,
 sel_expr FROM ...
DBMS WITH CURSOR cursor ALIAS existing_aliases,
 prolfx_alias

DM_GEN_PREPEND
Adds sel_expr to the beginning of the select list, and prolfx_alias is added before the existing aliases. This produces the following statements: 
DBMS DECLARE cursor FOR SELECT sel_expr,
 existing_select_list FROM ...
DBMS WITH CURSOR cursor ALIAS prolfx_alias,
 existing_aliases

DM_GEN_REPLACE_ALL
sel_expr replaces the previous select list, and prolfx_alias replaces the existing aliases. This produces the following statements: 
DBMS DECLARE cursor FOR SELECT sel_expr FROM ...
DBMS WITH CURSOR cursor ALIAS prolfx_alias

Returns

Description

dm_gen_change_select_list allows you to edit the select list built using the SQL generator. The data 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. You must call this function once for each change you wish to make.

By default, the SQL generator builds the select list from the widgets whose use_in_select property is set to PV_YES. For more information on the SQL generator, 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 that processes the TM_SEL_BUILD_PERFORM event. If you are modifying the select processing for a server view, call dm_gen_change_select_list from an event function attached to the first parent table view in the server view.

For more information on transaction event functions, refer to Chapter 32, "Writing Transaction Event Functions," in Application Development Guide.

Example

# JPL Procedure:
	# Adds pic1, a binary column, to the select list for the
	# current server view and sets bin_col1 as the target.
	# The Function property is set to binary_hook.
	
proc binary_hook (event)
	{
	vars retval(5) colexp(64)

if (event==TM_SEL_BUILD_PERFORM)
	  {
	    colexp=dm_gen_get_tv_alias\
	      (sm_tm_pinquire(TM_TV_NAME) ## ".pic1")
	    retval=dm_gen_change_select_list\
	      ("", colexp, "bin_col1", DM_GEN_APPEND)

# The number of occurrences for bin_col1 is set to match the 
	# number of occurrences of another column in the table.
 
    if (retval == 0)
    {
      retval=sm_n_max_occur("name")
      dbms binary bin_col1[:retval](1024)
    }
  }
  return TM_PROCEED}

See Also

dm_gen_sql_info