create table type_table_info (
    table_name varchar2(30),
    column_name varchar2(30),
    data_type varchar2(100)
  )  

create or replace procedure convert_date_to_timestamp
/**************************
  function: 将数据库中所有的表中含DATE类型的字段改为TIMESTAMP类型；
  需要建立下列类型表：
  create table type_table_info (
    table_name varchar2(30),
    column_name varchar2(30),
    data_type varchar2(100)
  )  
***************************/
is
  v_query_base_sql varchar2(100) := ‘SELECT table_name, column_name, data_type FROM all_tab_cols WHERE table_name = ‘‘‘;
  v_query_table_sql varchar2(150);
  v_alter_sql varchar2(100);

  type table_type is table of type_table_info%rowtype;
  table_array table_type;

begin
  for c_tabs in (
       select table_name from user_tables where table_name <> ‘type_table_info‘ 
    )
    loop
      v_query_table_sql := v_query_base_sql || c_tabs.table_name || ‘‘‘‘;
      execute immediate v_query_table_sql bulk collect into table_array;
      for i in table_array.first .. table_array.last
        loop
          --DBMS_OUTPUT.put_line(table_array(i).column_name || ‘:‘ || table_array(i).data_type);
          if table_array(i).data_type = ‘DATE‘ then
            v_alter_sql := ‘alter table ‘ || table_array(i).table_name || ‘ modify ‘ || table_array(i).column_name || ‘ timestamp‘;
            DBMS_OUTPUT.put_line(table_array(i).column_name || ‘: ‘ || v_alter_sql);
            execute immediate v_alter_sql;
          end if;
          
        end loop;
    end loop;
end convert_date_to_timestamp;