改变字段类型？ [英] Alter field type?

问题描述

是否可以在不制作

a新表的情况下改变字段类型（从varchar到文本）？

问候，


BTJ

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有人写道：

我明白如果你向后播放Windows CD你听到很奇怪

撒旦的消息

有人回复：

它甚至比那更糟糕;玩转发它安装Windows

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提示9：规划师会忽略你的愿望如果您的

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Is it possible to alter field type (from varchar to text) without making
a new table?
Regards,

BTJ

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推荐答案

Am Do，den 26.08.2004 schrieb Bj？rn T Johansen um 9:48：

Hi,

Am Do, den 26.08.2004 schrieb Bj?rn T Johansen um 9:48:

是否可以改变字段类型（从varchar到text ）没有制作一张新桌子？

Is it possible to alter field type (from varchar to text) without making
a new table?

在8.0中我认为。

7.4.x中的常见做法是：


BEGIN工作;

ALTER TABLE yourtable ADD COLUMN临时文本;

UPDATE yourtable SET tempcolumn = origcolumn;

ALTER TABLE yourtable DROP COLUMN origcolumn;

ALTER TABLE yourtable RENAME tempcolumn TO o rigcolumn;

COMMIT工作;


由于文本和（无限制）varchar完全相同，

你可以逃脱修改系统表。

但我不建议这样做。


问候

Tino Wildenhain

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In 8.0 I think.
Common practice in 7.4.x is:

BEGIN work;
ALTER TABLE yourtable ADD COLUMN tempcolumn text;
UPDATE yourtable SET tempcolumn = origcolumn;
ALTER TABLE yourtable DROP COLUMN origcolumn;
ALTER TABLE yourtable RENAME tempcolumn TO origcolumn;
COMMIT work;

Since text and (unlimited) varchar are quite the same,
you could get away with modifying the system tables.
But I would not recomment to do so.

Regards
Tino Wildenhain
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Bj？rn T Johansen< bt*@havleik.no>写道：

Bj?rn T Johansen <bt*@havleik.no> writes:

是否可以在不制作新表的情况下改变字段类型（从varchar到文本）？

Is it possible to alter field type (from varchar to text) without making a new
table?

您可以添加新列，更新表以将新列设置为旧的

值。然后放弃旧列。然后你可能想把桌子抽真空。


在8.0中会有一个命令来做你想要的，但它仍然需要

do所有与上述相同的工作。


-

greg

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You can add a new column, update the table to set the new column to the old
value. then drop the old column. Then you might want to vacuum full the table.

In 8.0 there will be a command to do what you want, but it will still have to
do all the same work as I described above.

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看起来像食谱，thx ... :)


BTJ


Tino Wildenhain写道：

That looks like a recipe, thx... :)

BTJ

Tino Wildenhain wrote:

Am Do，den 26.08.2004 schrieb Bj？rn T Johansen嗯9：48：

Hi,

Am Do, den 26.08.2004 schrieb Bj?rn T Johansen um 9:48:

是否可以改变字段类型（从varchar到text）而不用
一张新桌子？

Is it possible to alter field type (from varchar to text) without making
a new table?

8.0我认为。
7.4.x中的常见做法是：

BEGIN工作;
ALTER TABLE yourtable ADD COLUMN临时文本;
UPDATE yourtable SET tempcolumn = origcolumn;
ALTER TABLE yourtable DROP COLUMN origcolumn;
ALTER TABLE yourtable RENAME tempcolumn TO origcolumn;
COMMIT工作;

由于文本和（无限制）varchar完全相同，
你可以通过修改系统表来逃避。
但我不建议做所以。

问候
Tino Wildenhain

In 8.0 I think.
Common practice in 7.4.x is:

BEGIN work;
ALTER TABLE yourtable ADD COLUMN tempcolumn text;
UPDATE yourtable SET tempcolumn = origcolumn;
ALTER TABLE yourtable DROP COLUMN origcolumn;
ALTER TABLE yourtable RENAME tempcolumn TO origcolumn;
COMMIT work;

Since text and (unlimited) varchar are quite the same,
you could get away with modifying the system tables.
But I would not recomment to do so.

Regards
Tino Wildenhain

-

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Bj？tn Johansen（BSc，MNIF）

执行经理
bt*@havleik.no Havleik Consulting
电话：[phone] Bj？rneb？rstien 57

传真：[phone] N-1348 Rykkinn

Cellular：+ 47 926 93 298 http://www.havleik.no

----------------- -------------------------------------------------- ----------------------------

有人写道：

我明白如果你向后播放Windows CD你会听到奇怪的声音

撒旦的消息

有人回复：

它是更糟糕的是;玩转发它安装Windows

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Bj?rn T Johansen (BSc,MNIF)
Executive Manager
bt*@havleik.no Havleik Consulting
Phone : [phone] Bj?rneb?rstien 57
Fax : [phone] N-1348 Rykkinn
Cellular : [phone] http://www.havleik.no
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To which someone replied:
"It''s even worse than that; play it forwards and it installs Windows"
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