ALTER TABLE，在非空列中设置空值，PostgreSQL 9.1
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ALTER TABLE, set null in not null column, PostgreSQL 9.1
提问by Brian Brown
I have a table with not null column, How to set a null value in this column as default?
我有一个非空列的表，如何将此列中的空值设置为默认值？
I mean, I want to do something like this:
我的意思是，我想做这样的事情：
postgres=# ALTER TABLE person ALTER COLUMN phone SET NULL;
but it shows:
但它显示：
postgres=# ALTER TABLE person ALTER COLUMN phone SET NULL;
ERROR: syntax error at or near "NULL"
LINE 1: ALTER TABLE person ALTER COLUMN phone SET NULL;
回答by a_horse_with_no_name
ALTER TABLE person ALTER COLUMN phone DROP NOT NULL;
More details in the manual: http://www.postgresql.org/docs/9.1/static/sql-altertable.html
手册中的更多详细信息：http: //www.postgresql.org/docs/9.1/static/sql-altertable.html
回答by Rigin Oommen
Execute the command in this format
以这种格式执行命令
ALTER TABLE tablename ALTER COLUMN columnname SET NOT NULL;
for setting the column to not null.
用于将列设置为非空。
回答by jainvikram444
First, Set :
ALTER TABLE person ALTER COLUMN phone DROP NOT NULL;
回答by Sunny Chawla
Execute the command in this format:ALTER [ COLUMN ] column { SET | DROP } NOT NULL
以这种格式执行命令：ALTER [ COLUMN ] column { SET | DROP } NOT NULL
