Need help to redesign legacy SQL Script

Question

Hello Experts,
I have the below code which produces a CREATE TRIGGER statement. as of now this does for updating. I need to re-design this code to add for inserting and deleting as well. I just need help in the structuring wise. I can build the logic for inserting and updating inside. I want to know how i can continue to get for "inserting" and "deleting" as well.
you will understand my question better if you go through main code, present output and required output format below.
I know this is a bad design first of all. but the below code is a legacy one. so i cant change the entire structure of the code :-( all i can do is to continue designing it to add new changes. Hence sought help from you all.
please help
SQL CODE:
WITH audit_tables
AS
   (SELECT object_name,
           MIN (column_id) min_col,
           MAX (column_id) max_col
    FROM   user_objects o,
           user_tab_columns c
    WHERE  o.object_name = 'CHR_VAL_DESC_A_T'
    AND    o.object_name = c.table_name
    GROUP BY object_name
SELECT txt
FROM (
SELECT ' CREATE OR REPLACE TRIGGER ' || REPLACE(object_name,'_A_T') || '_ADT_TRG' || CHR(13) ||
       '   AFTER INSERT ' || CHR(13) ||
       '   OR    UPDATE ' || CHR(13) ||
       '   OR    DELETE ' || CHR(13) ||
       '   ON ' || REPLACE(object_name,'_A_T','_T') || CHR(13) ||
       '   FOR EACH ROW ' || CHR(13) ||
       ' DECLARE ' || CHR(13) ||
       ' BEGIN ' || CHR(13) ||
       ' IF updating THEN ' || CHR(13) ||
       '   INSERT INTO ' || object_name || CHR(13) ||
       '   (' txt, object_name, 1 disp_order, 0 column_id
FROM audit_tables
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM (SELECT 
        CASE
          WHEN max_col = column_id THEN
            '    '||column_name
          ELSE
            '    '||column_name || ','
          END AS txt, object_name, 2 disp_order, column_id
      FROM  audit_tables t,
            user_tab_columns C
      WHERE c.table_name = t.object_name
      ORDER BY c.column_id ASC)
UNION ALL
SELECT '   )' || CHR(13) ||
       '   VALUES ' || CHR(13) ||
       '   (', object_name, 3 disp_order, 0
FROM audit_tables t
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM (SELECT
        CASE
          WHEN max_col = column_id THEN
            CASE
              WHEN SUBSTR(column_name,1,2) = 'N_' THEN
                '    :NEW.'||decode(substr(column_name,1,2),'N_',substr(column_name,3))||');'
              WHEN SUBSTR(column_name,1,2) = 'O_' THEN
                '    :OLD.'||decode(substr(column_name,1,2),'O_',substr(column_name,3))||');'
              WHEN min_col = column_id THEN
                '    1'
              WHEN column_id = 2 THEN
                '     ''I'''
              WHEN column_id = 3 THEN
                '    SYSDATE'
              ELSE
              '    :NEW.'||column_name||');'
            END
          ELSE
            CASE
              WHEN SUBSTR(column_name,1,2) = 'N_' THEN
                '    :NEW.'||decode(substr(column_name,1,2),'N_',substr(column_name,3))||','
              WHEN SUBSTR(column_name,1,2) = 'O_' THEN
                '    :OLD.'||decode(substr(column_name,1,2),'O_',substr(column_name,3))||','
              WHEN min_col = column_id THEN
                '    1'||','
              WHEN column_id = 2 THEN
                '    ''I'''||','
              WHEN column_id = 3 THEN
                '    SYSDATE' ||','
              ELSE
                '    :NEW.'||column_name||','
               END
          END AS txt,object_name, 4 disp_order, column_id
      FROM audit_tables t,
           user_tab_columns c
      WHERE c.table_name = t.object_name
      ORDER BY c.column_id ASC)
UNION ALL
SELECT 'END '||REPLACE(object_name,'_A_T') || '_ADT_TRG;' || CHR(13),
       object_name, 5 disp_order, 0
FROM    audit_tables)
ORDER BY object_name, disp_order, column_id
PRESENT OUTPUT:
CREATE OR REPLACE TRIGGER CHR_VAL_DESC_ADT_TRG
   AFTER INSERT
   OR    UPDATE
   OR    DELETE
   ON CHR_VAL_DESC_T
   FOR EACH ROW
DECLARE
BEGIN
IF updating THEN
   INSERT INTO CHR_VAL_DESC_A_T
    TXN_ID,                                  
    TXN_TYP,                                 
    ADT_DTTM,                                
    CHR_VAL_DESC_ID,                         
    CHR_VAL_ID,                              
    LANG_ID,                                 
    DESC_ID,                                 
    O_CHR_VAL_DESC,                          
    N_CHR_VAL_DESC,                          
    O_TRANS_STATE,                           
    N_TRANS_STATE,                           
    CRTD_BY,                                 
    CRTD_DTTM,                               
    O_UPD_BY,                                
    N_UPD_BY,                                
    O_UPD_DTTM,                              
    N_UPD_DTTM,                              
    O_LOCK_NUM,                              
    N_LOCK_NUM                               
   VALUES
    1,                                       
    'I',                                     
    SYSDATE,                                 
    :NEW.CHR_VAL_DESC_ID,                    
    :NEW.CHR_VAL_ID,                         
    :NEW.LANG_ID,                            
    :NEW.DESC_ID,                            
    :OLD.CHR_VAL_DESC,                       
    :NEW.CHR_VAL_DESC,                       
    :OLD.TRANS_STATE,                        
    :NEW.TRANS_STATE,                        
    :NEW.CRTD_BY,                            
    :NEW.CRTD_DTTM,                          
    :OLD.UPD_BY,                             
    :NEW.UPD_BY,                             
    :OLD.UPD_DTTM,                           
    :NEW.UPD_DTTM,                           
    :OLD.LOCK_NUM,                           
    :NEW.LOCK_NUM);                          
END CHR_VAL_DESC_ADT_TRG;
REQUIRED OUTPUT FORMAT:
CREATE OR REPLACE TRIGGER TRIGGER_NAME
   AFTER INSERT
   OR    UPDATE
   OR    DELETE
   ON TABLE_NAME
   FOR EACH ROW
DECLARE
BEGIN
IF updating THEN
   INSERT TABLE_NAME
    list of column names                               
   VALUES
IF inserting THEN
   INSERT TABLE_NAME
    list of column names                               
   VALUES
IF deleting THEN
   INSERT TABLE_NAME
    list of column names                               
   VALUES
END TRIGGER_NAME;

Answer 1

can anyone please help?
i tried adding with inserting and updating also..but when i tried to add deleting part the final output not comes in proper structure.
WITH audit_tables
AS
   (SELECT object_name,
           MIN (column_id) min_col,
           MAX (column_id) max_col
    FROM   user_objects o,
           user_tab_columns c
    WHERE  o.object_name IN ('CHR_VAL_DESC_A_T', 'CHR_VAL_A_T')
    AND    o.object_name = c.table_name
    GROUP BY object_name
SELECT txt
FROM (
SELECT ' CREATE OR REPLACE TRIGGER ' || REPLACE(object_name,'_A_T') || '_ADT_TRG' || CHR(13) ||
       '   AFTER INSERT ' || CHR(13) ||
       '   OR    UPDATE ' || CHR(13) ||
       '   OR    DELETE ' || CHR(13) ||
       '   ON ' || REPLACE(object_name,'_A_T','_T') || CHR(13) ||
       '   FOR EACH ROW ' || CHR(13) ||
       ' DECLARE ' || CHR(13) ||
       ' BEGIN ' || CHR(13) ||
       *' IF inserting THEN '* || CHR(13) ||
       '   INSERT INTO ' || object_name || CHR(13) ||
       '   (' txt, object_name, 1 disp_order, 0 column_id
FROM audit_tables
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM (SELECT 
        CASE
          WHEN max_col = column_id THEN
            '    '||column_name
          ELSE
            '    '||column_name || ','
          END AS txt, object_name, 2 disp_order, column_id
      FROM  audit_tables t,
            user_tab_columns C
      WHERE c.table_name = t.object_name
      ORDER BY c.column_id ASC)
UNION ALL
SELECT '   )' || CHR(13) ||
       '   VALUES ' || CHR(13) ||
       '   (', object_name, 3 disp_order, 0
FROM audit_tables t
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM (SELECT
        CASE
          WHEN max_col = column_id THEN
            CASE
              WHEN SUBSTR(column_name,1,2) = 'N_' THEN
                '    :NEW.'||decode(substr(column_name,1,2),'N_',substr(column_name,3))||');'
              WHEN SUBSTR(column_name,1,2) = 'O_' THEN
                '    NULL'||');'
              WHEN min_col = column_id THEN
                '    1'
              WHEN column_id = 2 THEN
                '     ''I'''
              WHEN column_id = 3 THEN
                '    SYSDATE'
              ELSE
              '    :NEW.'||column_name||');'
            END
          ELSE
            CASE
              WHEN SUBSTR(column_name,1,2) = 'N_' THEN
                '    :NEW.'||decode(substr(column_name,1,2),'N_',substr(column_name,3))||','
              WHEN SUBSTR(column_name,1,2) = 'O_' THEN
                '    NULL'||','
              WHEN min_col = column_id THEN
                '    1'||','
              WHEN column_id = 2 THEN
                '    ''I'''||','
              WHEN column_id = 3 THEN
                '    SYSDATE' ||','
              ELSE
                '    :NEW.'||column_name||','
               END
          END AS txt,object_name, 4 disp_order, column_id
      FROM audit_tables t,
           user_tab_columns c
      WHERE c.table_name = t.object_name
      ORDER BY c.column_id ASC)
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM(SELECT *' ELSIF updating THEN '* || CHR(13) ||
       '   INSERT INTO ' || object_name || CHR(13) ||
       '   (' txt, object_name, 5 disp_order, 0 column_id
FROM audit_tables
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM (SELECT 
        CASE
          WHEN max_col = column_id THEN
            '    '||column_name
          ELSE
            '    '||column_name || ','
          END AS txt, object_name, 6 disp_order, column_id
      FROM  audit_tables t,
            user_tab_columns C
      WHERE c.table_name = t.object_name
      ORDER BY c.column_id ASC)
UNION ALL
SELECT '   )' || CHR(13) ||
       '   VALUES ' || CHR(13) ||
       '   (', object_name, 7 disp_order, 0
FROM audit_tables t
UNION ALL
SELECT txt, object_name, disp_order, column_id
FROM (SELECT
        CASE
         WHEN max_col = column_id THEN
            CASE
              WHEN SUBSTR(column_name,1,2) = 'N_' THEN
                '    :NEW.'||decode(substr(column_name,1,2),'N_',substr(column_name,3))||');'
              WHEN SUBSTR(column_name,1,2) = 'O_' THEN
                '    :OLD.'||decode(substr(column_name,1,2),'O_',substr(column_name,3))||');'
              WHEN min_col = column_id THEN
                '    1'
              WHEN column_id = 2 THEN
                '     ''U'''
              WHEN column_id = 3 THEN
                '    SYSDATE'
              ELSE
              '    :NEW.'||column_name||');'
            END
          ELSE
            CASE
              WHEN SUBSTR(column_name,1,2) = 'N_' THEN
                '    :NEW.'||decode(substr(column_name,1,2),'N_',substr(column_name,3))||','
              WHEN SUBSTR(column_name,1,2) = 'O_' THEN
                '    :OLD.'||decode(substr(column_name,1,2),'O_',substr(column_name,3))||','
              WHEN min_col = column_id THEN
                '    1'||','
              WHEN column_id = 2 THEN
                '    ''U'''||','
              WHEN column_id = 3 THEN
                '    SYSDATE' ||','
              ELSE
                '    :NEW.'||column_name||','
            END
          END AS txt,object_name, 8 disp_order, column_id
      FROM audit_tables t,
           user_tab_columns c
      WHERE c.table_name = t.object_name
      ORDER BY c.column_id ASC)
UNION ALL
SELECT 'END IF;' || CHR(13) ||
       'END '||REPLACE(object_name,'_A_T') || '_ADT_TRG;' || CHR(13),
       object_name, 9 disp_order, 0
FROM    audit_tables)
ORDER BY object_name, disp_order, column_id)