postgresql----继承表INHERITS PARENT TABLE

时间 2019-11-10

标签 postgresql 继承 inherits parent table 栏目 Postgre SQL 繁體版

原文原文链接

使用INHERITS建立的新表会继承一个或多个父表，子表只会继承父表的表结构和NOT NULL，DEFAULT，CHECK三种约束，主键，外键和惟一键以及索引不会被继承，因此修改父表的结构（增删字段），NOT NULL，DEFAULT和CHECK约束会自动同步子表修改。spa

示例1.code

create table tbl_inherits_parent(
a int not null,
b varchar(32) not null default 'Got u',
c int check (c > 0),
d date not null
);

test=# alter table tbl_inherits_parent add constraint pk_tbl_inherits_parent_a primary key(a);
ALTER TABLE

test=# alter table tbl_inherits_parent add constraint uk_tbl_inherits_parent_b_d unique (b,d);
ALTER TABLE

test=# create table tbl_inherits_partition() inherits (tbl_inherits_parent);
CREATE TABLE
test=# \d tbl_inherits_partition 
                    Table "public.tbl_inherits_partition"
 Column |         Type          |                  Modifiers                  
--------+-----------------------+---------------------------------------------
 a      | integer               | not null
 b      | character varying(32) | not null default 'Got u'::character varying
 c      | integer               | 
 d      | date                  | not null
Check constraints:
    "tbl_inherits_parent_c_check" CHECK (c > 0)
Inherits: tbl_inherits_parent

示例2.blog

test=# alter table tbl_inherits_parent add column e int not null default 0;
ALTER TABLE
test=# alter table tbl_inherits_parent alter column b set default 'try me';
ALTER TABLE
test=# \d tbl_inherits_partition 
                     Table "public.tbl_inherits_partition"
 Column |         Type          |                  Modifiers                   
--------+-----------------------+----------------------------------------------
 a      | integer               | not null
 b      | character varying(32) | not null default 'try me'::character varying
 c      | integer               | 
 d      | date                  | not null
 e      | integer               | not null default 0
Check constraints:
    "tbl_inherits_parent_c_check" CHECK (c > 0)
Inherits: tbl_inherits_parent

示例3.继承

除继承父表以外，建立子表时能够增长本身的字段索引

test=# create table tbl_inherits_partition1(f int) inherits (tbl_inherits_parent);
CREATE TABLE
test=# \d tbl_inherits_partition1 
                    Table "public.tbl_inherits_partition1"
 Column |         Type          |                  Modifiers                   
--------+-----------------------+----------------------------------------------
 a      | integer               | not null
 b      | character varying(32) | not null default 'try me'::character varying
 c      | integer               | 
 d      | date                  | not null
 e      | integer               | not null default 0
 f      | integer               | 
Check constraints:
    "tbl_inherits_parent_c_check" CHECK (c > 0)
Inherits: tbl_inherits_parent

示例4.解除继承同步

test=# alter table tbl_inherits_partition1 no inherit tbl_inherits_parent;
ALTER TABLE
test=# \d tbl_inherits_partition1 
                    Table "public.tbl_inherits_partition1"
 Column |         Type          |                  Modifiers                   
--------+-----------------------+----------------------------------------------
 a      | integer               | not null
 b      | character varying(32) | not null default 'try me'::character varying
 c      | integer               | 
 d      | date                  | not null
 e      | integer               | not null default 0
 f      | integer               | 
Check constraints:
    "tbl_inherits_parent_c_check" CHECK (c > 0)