Oracle for 循环

-- 循环输出数值
begin
  for i in 1 .. 100 loop
    sys.dbms_output.put_line(i);
  end loop;
end;

-- 循环累加
declare
  var_sum number := 0;
begin
  for i in 1 .. 100 loop
    var_sum := var_sum + i;
  end loop;
  sys.dbms_output.put_line(var_sum); -- 5050
end;

-- 批量插入
begin
  for i in 1 .. 100 loop
    -- todo: insert into some_table(field1, field2, ..., fieldN) values(valie1, value2, ..., valueN);
    sys.dbms_output.put_line('insert: ' || to_char(i));
  end loop;
  commit;
  sys.dbms_output.put_line('多次insert,统一commit');
end;

-- 批量更新
begin
  for i in 1 .. 100 loop
    -- todo: update some_table set fieldN = valueN where fieldN = valueN;
    sys.dbms_output.put_line('update: ' || to_char(i));
  end loop;
  commit;
  sys.dbms_output.put_line('多次update,统一commit');
end;

-- 查询你能管理的所有用户信息
select user_id, username, created from all_users;

-- 循环输出用户表信息
begin
  for cur_row in (select user_id, username, created from all_users) loop
    sys.dbms_output.put_line(cur_row.username);
  end loop;
end;
-- 当循环对象是比较长串的SQL时,建议提取游标,方便后续查看和维护

-- 循环输出用户表信息(游标提取)
declare
  -- 提取游标对象,方便单独维护SQL
  cursor cursor_all_users is
    select user_id, username, created from all_users;
  -- 游标子项(更多的时候,表是动态表,所以这句声明也可以省略)
  -- cursor_user all_users%rowtype;
begin
  for cursor_user in cursor_all_users loop
    dbms_output.put_line(cursor_user.username);
  end loop;
end;