使用额外的列将数据从旧表迁移到新表 Postgres

Question

表结构：

旧表结构：

新表结构：

询问：

INSERT INTO hotel (id, name, hotel_type, active, parent_hotel_id)
SELECT id, name, hotel_type, active, parent_hotel_id 
FROM dblink('demopostgres', 'SELECT id, name, hotel_type, active, parent_hotel_id FROM hotel')
    AS data(id bigint, name character varying, hotel_type character varying, active boolean, parent_hotel_id bigint);

出现以下错误：

ERROR: null value in column "created_by" violates not-null constraint DETAIL: Failing row contains (1, Test Hotel, THREE_STAR, t, null, null, null, null, null, null). SQL state：23502

我试图插入其他必需的列

注意：created_by 为 Jsonb

created_by = '{
    "id": 1,
    "email": "tes@localhost",
    "login": "test",
    "lastName": "Test",
    "firstName": "Test",
    "displayName": "test"
}'
created_date = '2020-02-22 16:09:08.346'

从旧表移动数据时，如何传递 created_by 和 created_date 列的默认值？

Answer 1

有几种选择。

首先，INSERT 失败，因为该字段不是 NULL。 您可以更改表（ https://www.postgresql.org/docs/12/sql-altertable.html）以取消设置导入，使用值更新字段并重置NOT Z6C3E226B4B088EC2918

ALTER [ COLUMN ] column_name { SET | DROP } NOT NULL

二，正如@XraySensei 所说，您可以使用 ALTER TABLE 将 DEFAULT 值添加到表中：

ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
    action [, ... ]
ALTER [ COLUMN ] column_name SET DEFAULT expression

第三个选项是将默认值嵌入到查询中：

create table orig_test(id integer NOT NULL, fld_1 varchar, fld_2 integer NOT NULL);

insert into orig_test(id, fld_1, fld_2) values (1, 'test', 4);
insert into orig_test(id, fld_1, fld_2) values (2, 'test', 7);

insert into default_test (id, fld_1, fld_2) select id, fld_1, fld_2 from orig_test ;
ERROR:  null value in column "fld_3" violates not-null constraint
DETAIL:  Failing row contains (1, test, 4, null).

insert into default_test (id, fld_1, fld_2, fld_3) select id, fld_1, fld_2, '06/14/2020' AS fld_3 from orig_test ;
INSERT 0 2