PostgreSQL:SELECT INTO正在更改字段的数据类型

我有一张桌子如下:

CREATE TABLE IF NOT EXISTS foo_raw
(
    time   TIMESTAMPTZ NOT NULL,
    volume INTEGER,                  <-- note source field is of type integer
    price  DOUBLE PRECISION
);

COPY foo_raw(time,volume,price) FROM 'raw_data.csv' DELIMITER ',' CSV

然后我做一个 SELECT INTO 我正在合并一个新表 time

选择进入

SELECT
    time, 
    SUM(volume)::integer AS volume,          <-- note typecast to integer here
    SUM(volume * price) / SUM(volume) AS price
INTO
    foo
FROM
    foo_raw
GROUP BY
    time
ORDER BY
    time;

如果我描述一下我的新桌子,我会发现 volume 字段的类型为 numeric ,不是 integer .

pg=# \d foo
                   Table "public.foo"
 Column |           Type           | Collation | Nullable | Default 
--------+--------------------------+-----------+----------+---------
 time   | timestamp with time zone |           | not null | 
 volume | numeric                  |           |          |     
 price  | double precision         |           |          | 

你会在我的日记里记下 选择进入 我试着把结果打印出来 SUM(volume)

问题

如何强制字段为类型 整数 ?