1 為表和列建立備註

drop table if exists test;
create table test(
    objectid serial not null,
    num integer not null,
	constraint pk_test_objectid primary key (objectid),
	constraint ck_test_num check(num < 123 ),
);
comment on table test is '我是表';
comment on column test.objectid is '我是唯一主鍵';
comment
 
 on column test.num is '數量欄位';
comment on constraint pk_test_objectid on test is '我是約束,唯一主鍵';
comment on constraint ck_test_num on test is '我是約束,num欄位必須小於123';
\dS+ test;

2 為檢視和列建立備註

drop view if exists vtest;
create or replace view vtest
	as	select 1 as col1, 'a' as col2, now() as col3;
comment
 
 on view vtest is '檢視備註';
comment on column vtest.col1 is '第一列備註,integer型別';
comment on column vtest.col2 is '第二列備註,字元型別';
comment on column vtest.col3 is '第三列備註,日期時間型別';

3 comment語法

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 |
  PUBLICATION object_name |
  ROLE object_name |
  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'

where aggregate_signature is:

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

注意:SQL 標準中沒有COMMENT命令。