今天就跟大家聊聊有关怎么在PostgreSQL中为表或视图创建备注，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。
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1 为表和列创建备注
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 '我是主键';
comment on column test.num is '数量字段';
comment on constraint pk_test_objectid on test is '我是约束,主键';
comment on constraint ck_test_num on test is '我是约束,num字段必须小于123';
\dS+ test;
2 为视图和列创建备注
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 '视图备注';
comment on column vtest.col1 is '第一列备注,integer类型';
comment on column vtest.col2 is '第二列备注,字符类型';
comment on column vtest.col3 is '第三列备注,日期时间类型';
3 comment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 |
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 标准中没有COMMENT命令。
补充：postgre 查询注释_PostgreSQL查询表以及字段的备注
查询所有表名称以及字段含义
select c.relname 表名,cast(obj_description(relfilenode,'pg_class') as varchar) 名称,a.attname 字段,d.description 字段备注,concat_ws('',t.typname,SUBSTRING(format_type(a.atttypid,a.atttypmod) from '.∗')) as 列类型 from pg_class c,pg_attribute a,pg_type t,pg_description d
where a.attnum>0 and a.attrelid=c.oid and a.atttypid=t.oid and d.objoid=a.attrelid and d.objsubid=a.attnum
and c.relname in (select tablename from pg_tables where schemaname='public' and position('_2' in tablename)=0) order by c.relname,a.attnum查看所有表名
select tablename from pg_tables where schemaname='public' and position('_2' in tablename)=0;
select * from pg_tables;查看表名和备注
select relname as tabname,cast(obj_description(relfilenode,'pg_class') as varchar) as comment from pg_class c
where relname in (select tablename from pg_tables where schemaname='public' and position('_2' in tablename)=0);
select * from pg_class;查看特定表名备注
select relname as tabname,
cast(obj_description(relfilenode,'pg_class') as varchar) as comment from pg_class c
where relname ='表名';
查看特定表名字段
select a.attnum,a.attname,concat_ws('',t.typname,SUBSTRING(format_type(a.atttypid,a.atttypmod) from '.∗')) as type,d.description from pg_class c,pg_attribute a,pg_type t,pg_description d
where c.relname='表名' and a.attnum>0 and a.attrelid=c.oid and a.atttypid=t.oid and d.objoid=a.attrelid and d.objsubid=a.attnum;看完上述内容，你们对怎么在PostgreSQL中为表或视图创建备注有进一步的了解吗？如果还想了解更多知识或者相关内容，请关注创新互联行业资讯频道，感谢大家的支持。
文章题目：怎么在PostgreSQL中为表或视图创建备注-创新互联
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