如何在Postgresql数据库中添加不允许为空的列? [英] How can I add a column that doesn't allow nulls in a Postgresql database?

问题描述

我使用以下查询(已针对Internet进行了消毒)在我的Postgresql数据库中添加新的"NOT NULL"列:

I'm adding a new, "NOT NULL" column to my Postgresql database using the following query (sanitized for the Internet):

ALTER TABLE mytable ADD COLUMN mycolumn character varying(50) NOT NULL;

每次运行此查询时，都会收到以下错误消息:

Each time I run this query, I receive the following error message:

ERROR:  column "mycolumn" contains null values

我很困惑.我要去哪里错了?

I'm stumped. Where am I going wrong?

注意:我主要使用pgAdmin III(1.8.4)，但是当我从Terminal内部运行SQL时，我收到了相同的错误.

NOTE: I'm using pgAdmin III (1.8.4) primarily, but I received the same error when I ran the SQL from within Terminal.

推荐答案

您必须设置默认值.

ALTER TABLE mytable ADD COLUMN mycolumn character varying(50) NOT NULL DEFAULT 'foo';

... some work (set real values as you want)...

ALTER TABLE mytable ALTER COLUMN mycolumn DROP DEFAULT;

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