除普通的建表语句”create table table_name(columns);”之外，还可以根据现有表快速的创建新表:
一.使用create table … (like …)创建一个和原表结构相同的新表，根据INCLUDING保留原表的约束，索引等。
create table table_name (like parent_table {INCLUDING|EXCLUDING}{DEFAULTS|CONSTRAINTS|INDEXES|STORAGE|COMMENTS|ALL});
直接使用LIKE不使用INCLUDING，新表只保留原表的表结构和NOT NULL约束，但是使用INCLUDING CONSTRAINTS配置会保留了主键，唯一键，CHECK约束，并不会保留外键约束。
示例：
1.创建示例表
test=# create table tbl_inherits_test (a int not null); CREATE TABLE test=# alter table tbl_inherits_test add constraint pk_tbl_inherits_test_a primary key(a); ALTER TABLEtest=# create table tbl_inherits_parent( a int not null, b varchar(32) not null default 'got u', c int, d date); 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 fk_tbl_inherits_parent_a foreign key(a) references tbl_inherits_test(a); ALTER TABLE test=# alter table tbl_inherits_parent add constraint ck_tbl_inherits_parent_c check (c>10); ALTER TABLE test=# alter table tbl_inherits_parent add constraint uk_tbl_inherits_parent_b_d unique (b,d); ALTER TABLE
test=# create index idx_tbl_inherits_parent_d on tbl_inherits_parent using btree (d);
CREATE INDEX
2.使用LIKE创建表
test=# create table tbl_inherits_partition (like tbl_inherits_parent including constraints including indexes including defaults); CREATE TABLE test=# /d tbl_inherits_parent Table "public.tbl_inherits_parent" Column | Type | Modifiers --------+-----------------------+--------------------------------------------- a | integer | not null b | character varying(32) | not null default 'got u'::character varying c | integer | d | date | Indexes: "pk_tbl_inherits_parent_a" PRIMARY KEY, btree (a) "uk_tbl_inherits_parent_b_d" UNIQUE CONSTRAINT, btree (b, d) "idx_tbl_inherits_parent_d" btree (d) Check constraints: "ck_tbl_inherits_parent_c" CHECK (c > 10) Foreign-key constraints: "fk_tbl_inherits_parent_a" FOREIGN KEY (a) REFERENCES tbl_inherits_test(a) 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 | Indexes: "tbl_inherits_partition_pkey" PRIMARY KEY, btree (a) "tbl_inherits_partition_b_d_key" UNIQUE CONSTRAINT, btree (b, d) "tbl_inherits_partition_d_idx" btree (d) Check constraints: "ck_tbl_inherits_parent_c" CHECK (c > 10)
二、使用create table … as table … with {data|no data}创建一个和原表结构相同的新表，保留或不保留数据，但是不会继承原表的约束，索引等。
test=# insert into tbl_inherits_test values (1); INSERT 0 1 test=# insert into tbl_inherits_parent (a,b,c,d) values(1,'sss',12,'2016-06-22 17:00:00'); INSERT 0 1 test=# test=# create table tbl_inherits_partition1 as table tbl_inherits_parent with data; SELECT 1 test=# select * from tbl_inherits_partition1 ; a | b | c | d ---+-----+----+------------ 1 | sss | 12 | 2016-06-22 (1 row) test=# /d tbl_inherits_partition1 Table "public.tbl_inherits_partition1" Column | Type | Modifiers --------+-----------------------+----------- a | integer | b | character varying(32) | c | integer | d | date | test=# test=# test=# create table tbl_inherits_partition2 as table tbl_inherits_parent with no data; SELECT 0 test=# /d tbl_inherits_partition2 Table "public.tbl_inherits_partition2" Column | Type | Modifiers --------+-----------------------+----------- a | integer | b | character varying(32) | c | integer | d | date | test=# select * from tbl_inherits_partition2; a | b | c | d ---+---+---+--- (0 rows) test=#
三、使用select * into new_table from table将结果集保存在新表中，但是只能执行一次。
test=# select * into tbl_inherits_partition3 from tbl_inherits_parent ; SELECT 1 test=# /d tbl_inherits_partition3 Table "public.tbl_inherits_partition3" Column | Type | Modifiers --------+-----------------------+----------- a | integer | b | character varying(32) | c | integer | d | date | test=# select * from tbl_inherits_partition3 ; a | b | c | d ---+-----+----+------------ 1 | sss | 12 | 2016-06-22 (1 row)
四、使用create table new_table as select * from table将结果集保存在新表中。
test=# create table tbl_inherits_partition4 as select * from tbl_inherits_parent ; SELECT 1 test=# /d tbl_inherits_partition4 Table "public.tbl_inherits_partition4" Column | Type | Modifiers --------+-----------------------+----------- a | integer | b | character varying(32) | c | integer | d | date | test=# select * from tbl_inherits_partition4 ; a | b | c | d ---+-----+----+------------ 1 | sss | 12 | 2016-06-22 (1 row)
原创文章，作者：奋斗，如若转载，请注明出处：https://blog.ytso.com/4879.html