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  • SQL语法 /
  • DDL语句

DDL语句

更新时间:2024-04-15 21:9:36

CREATE DATABASE

说明:

创建一个新数据库。

语法:

CREATE DATABASE name
    [ [ WITH ] [ OWNER [=] user_name ]
           [ TEMPLATE [=] template ]
           [ ENCODING [=] encoding ]
           [ LOCALE [=] locale ]
           [ LC_COLLATE [=] lc_collate ]
           [ LC_CTYPE [=] lc_ctype ]
           [ TABLESPACE [=] tablespace_name ]
           [ ALLOW_CONNECTIONS [=] allowconn ]
           [ CONNECTION LIMIT [=] connlimit ] 
           [ IS_TEMPLATE [=] istemplate ] ]

示例:

-- 创建一个新数据库:
CREATE DATABASE lusiadas;

--在一个默认表空间salesspace中创建一个被用户salesapp拥有的新数据库sales:
CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

ALTER DATABASE

说明:

更改一个数据库

语法:

ALTER DATABASE name [ [ WITH ] option [ ... ] ]

这里 option 可以是:

    ALLOW_CONNECTIONS allowconn
    CONNECTION LIMIT connlimit
    IS_TEMPLATE istemplate

ALTER DATABASE name RENAME TO new_name

ALTER DATABASE name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }

ALTER DATABASE name SET TABLESPACE new_tablespace

ALTER DATABASE name SET configuration_parameter { TO | = } { value | DEFAULT }
ALTER DATABASE name SET configuration_parameter FROM CURRENT
ALTER DATABASE name RESET configuration_parameter
ALTER DATABASE name RESET ALL

示例:

--要在数据库test中默认禁用索引扫描:
ALTER DATABASE test SET enable_indexscan TO off;

DROP DATABASE

说明:

移除一个数据库

语法:

DROP DATABASE [ IF EXISTS ] name [ [ WITH ] ( option [, ...] ) ]

其中选项 可以是:

    FORCE

示例:

--移除数据库adb01,若adb01不存在,会报错。
DROP DATABASE adb01;

--移除数据库adb01,即使adb01不存在,也不会报错。
DROP DATABASE IF EXISTS adb01;

CREATE TABLE

说明:

创建数据库表格。表名必需在同一模式中的其它表、 序列、索引、视图或外部表名字中唯一。

语法:

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name ( [
  { column_name data_type [ COLLATE collation ] [ column_constraint [ ... ] ]
    | table_constraint
    | LIKE source_table [ like_option ... ] }
    [, ... ]
] )
[ INHERITS ( parent_table [, ... ] ) ]
[ PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [, ... ] ) ]
[ USING method ]
[ WITH ( storage_parameter [= value] [, ... ] ) | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE tablespace_name ]

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name
    OF type_name [ (
  { column_name [ WITH OPTIONS ] [ column_constraint [ ... ] ]
    | table_constraint }
    [, ... ]
) ]
[ PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [, ... ] ) ]
[ USING method ]
[ WITH ( storage_parameter [= value] [, ... ] ) | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE tablespace_name ]

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name
    PARTITION OF parent_table [ (
  { column_name [ WITH OPTIONS ] [ column_constraint [ ... ] ]
    | table_constraint }
    [, ... ]
) ] { FOR VALUES partition_bound_spec | DEFAULT }
[ PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [, ... ] ) ]
[ USING method ]
[ WITH ( storage_parameter [= value] [, ... ] ) | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE tablespace_name ]

示例:

以下创建了一张表名为COMPANY表格,主键为ID,NOT NULL表示字段不允许包含NULL值:

CREATE TABLE COMPANY(
   ID INT PRIMARY KEY     NOT NULL,
   NAME           TEXT    NOT NULL,
   AGE            INT     NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);

ALTER TABLE

说明:

更改一个表的定义

语法:

ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
    action [, ... ]
ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
    RENAME [ COLUMN ] column_name TO new_column_name
ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
    RENAME CONSTRAINT constraint_name TO new_constraint_name
ALTER TABLE [ IF EXISTS ] name
    RENAME TO new_name
ALTER TABLE [ IF EXISTS ] name
    SET SCHEMA new_schema
ALTER TABLE ALL IN TABLESPACE name [ OWNED BY role_name [, ... ] ]
    SET TABLESPACE new_tablespace [ NOWAIT ]
ALTER TABLE [ IF EXISTS ] name
    ATTACH PARTITION partition_name { FOR VALUES partition_bound_spec | DEFAULT }
ALTER TABLE [ IF EXISTS ] name
    DETACH PARTITION partition_name

其中常用action可以是以下之一:

ADD [ COLUMN ] column_type [ column_constraint [ ... ] ]
DROP [ COLUMN ] column [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] column TYPE type [ USING expression ]
ALTER [ COLUMN ] column SET DEFAULT expression
ALTER [ COLUMN ] column DROP DEFAULT
ALTER [ COLUMN ] column { SET | DROP } NOT NULL
ALTER [ COLUMN ] column SET STATISTICS integer
ALTER [ COLUMN ] column SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
ADD table_constraint
DROP CONSTRAINT constraint_name [ RESTRICT | CASCADE ]
CLUSTER ON index_name
SET WITHOUT CLUSTER
SET WITHOUT OIDS
OWNER TO new_owner
SET TABLESPACE tablespace_name

示例:

--重命名一个现有的表:
ALTER TABLE distributors RENAME TO suppliers;

--为一列增加一个非空约束:
ALTER TABLE distributors ALTER COLUMN street SET NOT NULL;

--把一个表移动到一个不同的模式:
ALTER TABLE myschema.distributors SET SCHEMA yourschema;

DROP TABLE

说明:

移除一个表

语法:

DROP TABLE [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]

示例:

--移除department和company两张表,若表格不存在,会报错
DROP TABLE department, company;

--移除department表,即使表格不存在,也会报错
DROP TABLE IF EXISTS department;

CREATE VIEW

说明:

定义一个新视图

语法:

CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW name [ ( column_name [, ...] ) ]
    [ WITH ( view_option_name [= view_option_value] [, ... ] ) ]
    AS query
    [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]

示例:

--创建一个基于表格COMPANY的视图COMPANY_VIEW
CREATE VIEW COMPANY_VIEW AS SELECT ID, NAME, AGE FROM COMPANY;

ALTER VIEW

说明:

更改一个视图的定义

语法:

ALTER VIEW [ IF EXISTS ] name ALTER [ COLUMN ] column_name SET DEFAULT expression
ALTER VIEW [ IF EXISTS ] name ALTER [ COLUMN ] column_name DROP DEFAULT
ALTER VIEW [ IF EXISTS ] name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }
ALTER VIEW [ IF EXISTS ] name RENAME TO new_name
ALTER VIEW [ IF EXISTS ] name SET SCHEMA new_schema
ALTER VIEW [ IF EXISTS ] name SET ( view_option_name [= view_option_value] [, ... ] )
ALTER VIEW [ IF EXISTS ] name RESET ( view_option_name [, ... ] )

示例:

--把视图foo重命名为bar:
ALTER VIEW foo RENAME TO bar;

--为视图a_view的列ts附加一个默认列值
ALTER VIEW a_view ALTER COLUMN ts SET DEFAULT now();

DROP VIEW

说明:

移除一个视图

语法:

DROP VIEW [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]

示例:

--移除视图COMPANY_VIEW,若视图不存在会报错
DROP VIEW COMPANY_VIEW;

--移除视图COMPANY_VIEW,即使视图不存在,也不会报错
DROP VIEW IF EXISTS COMPANY_VIEW;

CREATE INDEX

说明:

定义一个新索引

语法:

CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] name ] ON [ ONLY ] table_name [ USING method ]
    ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass [ ( opclass_parameter = value [, ... ] ) ] ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] )
    [ INCLUDE ( column_name [, ...] ) ]
    [ WITH ( storage_parameter [= value] [, ... ] ) ]
    [ TABLESPACE tablespace_name ]
    [ WHERE predicate ]

示例:

--在表films中的列title上创建一个 B-树索引:
CREATE UNIQUE INDEX title_idx ON films (title);

ALTER INDEX

说明:

更改一个索引的定义

语法:

ALTER INDEX [ IF EXISTS ] name RENAME TO new_name
ALTER INDEX [ IF EXISTS ] name SET TABLESPACE tablespace_name
ALTER INDEX name ATTACH PARTITION index_name
ALTER INDEX name DEPENDS ON EXTENSION extension_name
ALTER INDEX [ IF EXISTS ] name SET ( storage_parameter [= value] [, ... ] )
ALTER INDEX [ IF EXISTS ] name RESET ( storage_parameter [, ... ] )
ALTER INDEX [ IF EXISTS ] name ALTER [ COLUMN ] column_number
    SET STATISTICS integer
ALTER INDEX ALL IN TABLESPACE name [ OWNED BY role_name [, ... ] ]
    SET TABLESPACE new_tablespace [ NOWAIT ]

示例:

--将索引distributors重命名为suppliers:
ALTER INDEX distributors RENAME TO suppliers;

--把索引distributors移动到表空间fasttablespace中:
ALTER INDEX distributors SET TABLESPACE fasttablespace;

DROP INDEX

说明:

移除一个索引

语法:

DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]

示例:

--移除索引title_idx:
DROP INDEX title_idx;

CREATE FUNCTION

说明:

定义一个新函数

语法:

CREATE [ OR REPLACE ] FUNCTION
    name ( [ [ argmode ] [ argname ] argtype [ { DEFAULT | = } default_expr ] [, ...] ] )
    [ RETURNS rettype
      | RETURNS TABLE ( column_name column_type [, ...] ) ]
  { LANGUAGE lang_name
    | TRANSFORM { FOR TYPE type_name } [, ... ]
    | WINDOW
    | IMMUTABLE | STABLE | VOLATILE | [ NOT ] LEAKPROOF
    | CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT
    | [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
    | PARALLEL { UNSAFE | RESTRICTED | SAFE }
    | COST execution_cost
    | ROWS result_rows
    | SUPPORT support_function
    | SET configuration_parameter { TO value | = value | FROM CURRENT }
    | AS 'definition'
    | AS 'obj_file', 'link_symbol'
  } ...


示例:

--创建一个简单加法运算函数:
CREATE FUNCTION add(integer, integer) RETURNS integer
    AS 'select $1 + $2;'
    LANGUAGE SQL
    IMMUTABLE
    RETURNS NULL ON NULL INPUT;

ALTER FUNCTION

说明:

更改一个函数的定义

语法:

ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    action [ ... ] [ RESTRICT ]
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    RENAME TO new_name
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    OWNER TO { new_owner | CURRENT_USER | SESSION_USER }
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    SET SCHEMA new_schema
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    [ NO ] DEPENDS ON EXTENSION extension_name

其中 action 是以下之一:

    CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT
    IMMUTABLE | STABLE | VOLATILE | [ NOT ] LEAKPROOF
    [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
    PARALLEL { UNSAFE | RESTRICTED | SAFE }
    COST execution_cost
    ROWS result_rows
    SUPPORT support_function
    SET configuration_parameter { TO | = } { value | DEFAULT }
    SET configuration_parameter FROM CURRENT
    RESET configuration_parameter
    RESET ALL

示例:

--把用于类型integer的函数sqrt 重命名为square_root:
ALTER FUNCTION sqrt(integer) RENAME TO square_root;

--要把用于类型integer的函数sqrt 的模式改为maths:
ALTER FUNCTION sqrt(integer) SET SCHEMA maths;

DROP FUNCTION

说明:

移除一个函数

语法:

DROP FUNCTION [ IF EXISTS ] name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] [, ...]
    [ CASCADE | RESTRICT ]

示例:

--移除sqrt对应的两个函数
DROP FUNCTION sqrt(integer), sqrt(bigint);

CREATE PROCEDURE

说明:

定义一个新的过程

语法:

CREATE [ OR REPLACE ] PROCEDURE
    name ( [ [ argmode ] [ argname ] argtype [ { DEFAULT | = } default_expr ] [, ...] ] )
  { LANGUAGE lang_name
    | TRANSFORM { FOR TYPE type_name } [, ... ]
    | [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
    | SET configuration_parameter { TO value | = value | FROM CURRENT }
    | AS 'definition'
    | AS 'obj_file', 'link_symbol'
  } ...

示例:

--创建一个插入数据的过程,用CALL调用:
CREATE PROCEDURE insert_data(a integer, b integer)
LANGUAGE SQL
AS $$
INSERT INTO tbl VALUES (a);
INSERT INTO tbl VALUES (b);
$$;

CALL insert_data(1, 2);

ALTER PROCEDURE

说明:

更改一个过程的定义

语法:

ALTER PROCEDURE name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    action [ ... ] [ RESTRICT ]
ALTER PROCEDURE name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    RENAME TO new_name
ALTER PROCEDURE name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    OWNER TO { new_owner | CURRENT_USER | SESSION_USER }
ALTER PROCEDURE name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    SET SCHEMA new_schema
ALTER PROCEDURE name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    DEPENDS ON EXTENSION extension_name

其中action是下列之一:

    [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
    SET configuration_parameter { TO | = } { value | DEFAULT }
    SET configuration_parameter FROM CURRENT
    RESET configuration_parameter
    RESET ALL

示例:

--重命名具有两个integer类型参数的过程insert_data为insert_record:
ALTER PROCEDURE insert_data(integer, integer) RENAME TO insert_record;

--要把具有两个integer类型参数的过程insert_data的拥有者改为joe:
ALTER PROCEDURE insert_data(integer, integer) OWNER TO joe;

DROP PROCEDURE

说明:

移除一个过程

语法:

DROP PROCEDURE [ IF EXISTS ] name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] [, ...]
    [ CASCADE | RESTRICT ]

示例:

--移除过程insert_data:
DROP PROCEDURE insert_data();

CREATE SCHEMA

说明:

定义一个新模式

语法:

CREATE SCHEMA schema_name [ AUTHORIZATION role_specification ] [ schema_element [ ... ] ]
CREATE SCHEMA AUTHORIZATION role_specification [ schema_element [ ... ] ]
CREATE SCHEMA IF NOT EXISTS schema_name [ AUTHORIZATION role_specification ]
CREATE SCHEMA IF NOT EXISTS AUTHORIZATION role_specification

其中 role_specification 可以是:

    user_name
  | CURRENT_USER
  | SESSION_USER

示例:

--创建一个模式:
CREATE SCHEMA myschema;

--为用户joe创建一个模式,该模式也将被命名为 joe:
CREATE SCHEMA AUTHORIZATION joe;

ALTER SCHEMA

说明:

更改一个模式的定义

语法:

ALTER SCHEMA name RENAME TO new_name
ALTER SCHEMA name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }

示例:

--将模式sch_a重命名为sch_b:
ALTER SCHEMA sch_a RENAME TO sch_b;

DROP SCHEMA

说明:

移除一个模式

语法:

DROP SCHEMA [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]

示例:

--从数据库中移除模式mystuff及其中 所包含的对象:
DROP SCHEMA mystuff CASCADE;

CREATE USER

说明:

定义一个新的数据库角色

语法:

CREATE USER name [ [ WITH ] option [ ... ] ]

这里 option 可以是:

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'
    | IN ROLE role_name [, ...]
    | IN GROUP role_name [, ...]
    | ROLE role_name [, ...]
    | ADMIN role_name [, ...]
    | USER role_name [, ...]
    | SYSID uid

示例:

--创建一个超级用户,并赋予登录权限
CREATE USER user1 SUPERUSER PASSWORD '123456' LOGIN;

ALTER USER

说明:

更改一个数据库角色

语法:

ALTER USER role_specification [ WITH ] option [ ... ]

其中 option 可以是:

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'

ALTER USER name RENAME TO new_name

ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] SET configuration_parameter { TO | = } { value | DEFAULT }
ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] SET configuration_parameter FROM CURRENT
ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] RESET configuration_parameter
ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] RESET ALL

其中 role_specification 可以是:

    role_name
  | CURRENT_USER
  | SESSION_USER

示例:

--重命名用户
ALTER USER adb01 RENAME TO adb02;

DROP USER

说明:

移除一个数据库角色

语法:

DROP USER [ IF EXISTS ] name [, ...]

示例:

--移除用户adb01:
DROP USER IF EXISTS adb01;

CREATE ROLE

说明:

定义一个新的数据库角色

语法:

CREATE ROLE name [ [ WITH ] option [ ... ] ]

where option可以是:

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'
    | IN ROLE role_name [, ...]
    | IN GROUP role_name [, ...]
    | ROLE role_name [, ...]
    | ADMIN role_name [, ...]
    | USER role_name [, ...]
    | SYSID uid

示例:

--创建一个能登录但是没有口令的角色:
CREATE ROLE jonathan LOGIN;

--创建一个有口令的角色:
CREATE USER davide WITH PASSWORD 'jw8s0F4';

ALTER ROLE

说明:

更改一个数据库角色

语法:

ALTER ROLE role_specification [ WITH ] option [ ... ]

其中option可以是:

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'

ALTER ROLE name RENAME TO new_name

ALTER ROLE { role_specification | ALL } [ IN DATABASE database_name ] SET configuration_parameter { TO | = } { value | DEFAULT }
ALTER ROLE { role_specification | ALL } [ IN DATABASE database_name ] SET configuration_parameter FROM CURRENT
ALTER ROLE { role_specification | ALL } [ IN DATABASE database_name ] RESET configuration_parameter
ALTER ROLE { role_specification | ALL } [ IN DATABASE database_name ] RESET ALL

其中role_specification可以是:

    role_name
  | CURRENT_USER
  | SESSION_USER

示例:

--更改一个角色的口令:
ALTER ROLE davide WITH PASSWORD 'hu8jmn3';

--让一个角色能够创建其他角色和新的数据库:
ALTER ROLE miriam CREATEROLE CREATEDB;

DROP ROLE

说明:

移除一个数据库角色

语法:

DROP ROLE [ IF EXISTS ] name [, ...]

示例:

--删除一个角色:
DROP ROLE davide;

COMMENT

说明:

定义或者更改一个对象的注释

语法:

COMMENT ON
{
  ACCESS METHOD object_name |
  AGGREGATE aggregate_name ( aggregate_signature ) |
  CAST (source_type AS target_type) |
  COLLATION object_name |
  COLUMN relation_name.column_name |
  CONSTRAINT constraint_name ON table_name |
  CONSTRAINT constraint_name ON DOMAIN domain_name |
  CONVERSION object_name |
  DATABASE object_name |
  DOMAIN object_name |
  EXTENSION object_name |
  EVENT TRIGGER object_name |
  FOREIGN DATA WRAPPER object_name |
  FOREIGN TABLE object_name |
  FUNCTION function_name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] |
  INDEX object_name |
  LARGE OBJECT large_object_oid |
  MATERIALIZED VIEW object_name |
  OPERATOR operator_name (left_type, right_type) |
  OPERATOR CLASS object_name USING index_method |
  OPERATOR FAMILY object_name USING index_method |
  POLICY policy_name ON table_name |
  [ PROCEDURAL ] LANGUAGE object_name |
  PROCEDURE procedure_name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] |
  PUBLICATION object_name |
  ROLE object_name |
  ROUTINE routine_name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] |
  RULE rule_name ON table_name |
  SCHEMA object_name |
  SEQUENCE object_name |
  SERVER object_name |
  STATISTICS object_name |
  SUBSCRIPTION object_name |
  TABLE object_name |
  TABLESPACE object_name |
  TEXT SEARCH CONFIGURATION object_name |
  TEXT SEARCH DICTIONARY object_name |
  TEXT SEARCH PARSER object_name |
  TEXT SEARCH TEMPLATE object_name |
  TRANSFORM FOR type_name LANGUAGE lang_name |
  TRIGGER trigger_name ON table_name |
  TYPE object_name |
  VIEW object_name
} IS 'text'

其中 aggregate_signature 是:

* |
[ argmode ] [ argname ] argtype [ , ... ] |
[ [ argmode ] [ argname ] argtype [ , ... ] ] ORDER BY [ argmode ] [ argname ] argtype [ , ... ]


示例:

--为表mytable附加一段注释:
COMMENT ON TABLE mytable IS 'This is my table.';

TRUNCATE

说明:

清空一个表或者一组表

语法:

TRUNCATE [ TABLE ] [ ONLY ] name [ * ] [, ... ]
    [ RESTART IDENTITY | CONTINUE IDENTITY ] [ CASCADE | RESTRICT ]

示例:

--清空表bigtable和 fattable:
TRUNCATE bigtable, fattable;
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