plsqlのrowtype変数から動的列値を選択します

declare
  l_col_name varchar2(100);
  l_col_val varchar2(100);
  type t_col_tab is table of column_table%rowtype;
  l_col_tab t_col_tab;

  -- for dbms_sql
  l_c pls_integer;
  l_col_cnt pls_integer;
  l_desc_t dbms_sql.desc_tab;
  l_rc pls_integer;
  l_varchar varchar2(4000);
begin
  select * bulk collect into l_col_tab from column_table;

  -- create cursor and prepare from original query
  l_c := dbms_sql.open_cursor;
  dbms_sql.parse(c=>l_c, statement=>'select * from data_table',
    language_flag=>dbms_sql.native);
  dbms_sql.describe_columns(c => l_c, col_cnt => l_col_cnt,
    desc_t => l_desc_t);

  for i in 1..l_col_cnt loop
    dbms_sql.define_column(c=>l_c, position=>i,
      column=>l_varchar, column_size=>4000);
  end loop;

  l_rc := dbms_sql.execute(c=>l_c);

  while dbms_sql.fetch_rows(c=>l_c) > 0 loop
    for i in 1..l_col_cnt loop
      for j in 1..l_col_tab.count loop
        if l_desc_t(i).col_name = l_col_tab(j).column_name then
          -- same column
          dbms_sql.column_value(l_c, i, l_varchar);
          dbms_output.put_line('Row ' || dbms_sql.last_row_count
           || ': ' || l_desc_t(i).col_name
           || ' = ' || l_varchar);
        end if;
      end loop;
    end loop;
  end loop;

  dbms_sql.close_cursor(l_c);
end;
/

カーソルクエリが解析および実行され、テーブルの説明によって列名を比較できます。これは情報を印刷するだけですが、もちろん、必要なことは何でもできます。

次のように作成されたダミーテーブルを使用：

create table data_table(id number, column_1 date, column_2 varchar2(10), column_3 varchar2(10));
insert into data_table (id, column_1, column_2, column_3) values (1, date '2017-01-01', 'dummy', 'first');
insert into data_table (id, column_1, column_2, column_3) values (2, date '2017-02-01', 'dummy', 'second');

create table column_table (column_name varchar2(30));
insert into column_table (column_name) values ('ID');
insert into column_table (column_name) values ('COLUMN_3');

...これは出力を取得します：

Row 1: ID = 1
Row 1: COLUMN_3 = first
Row 2: ID = 2
Row 2: COLUMN_3 = second

PL/SQL procedure successfully completed.