VastbaseE100

COMMENT

COMMENT - 定义或更改对象的注释

语法格式

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 [ , ... ]

说明

• object_name
• relation_name.column_name
• aggregate_name
• constraint_name
• function_name
• operator_name
• policy_name
• procedure_name
• routine_name
• rule_name

• trigger_name

  要被注释的对象的名称。表、聚集、排序方式、转换、域、外部表、函数、 索引、操作符、操作符类、操作符族、存储过程、例程、序列、统计信息、文本搜索对象、类型和视图 的名称可以被模式限定。在注释一列时， relation_name必须 引用一个表、视图、组合类型或者外部表。

• table_name

• domain_name

  当在一个约束、触发器、规则或者策略上创建一段注释时，这些参数指定在其上定义 该对象的表或域的名称。

• source_type

  造型的源数据类型的名称。

• target_type

  造型的目标数据类型的名称。

• argmode

  一个函数，存储过程或者聚集函数的参数的模式：IN、 OUT、INOUT或者VARIADIC。 如果被省略，默认值是IN。注意 COMMENT并不真正关心 OUT参数，因为决定函数的身份只需要输入参数。因此 列出IN、INOUT和VARIADIC 参数就足够了。

• argname

  一个函数，存储过程或者聚集函数参数的名称。注意 COMMENT并不真正关心参数名称， 因为决定函数的身份只需要参数数据类型。

• argtype

  一个函数，存储过程或者聚集函数参数的数据类型。

• large_object_oid

  大对象的 OID。

• left_type

• right_type

  操作符的参数的数据类型（可以是模式限定的）。对一个前缀后后缀操作符 的缺失参数可以写NONE。

• PROCEDURAL

  这是一个噪声词。

• type_name

  该转换的数据类型的名称。

• lang_name

  该转换的语言的名称。

• text

  写成一个字符串的新注释。如果要删除注释，写成NULL。

注意事项

当前对查看注释没有安全机制：任何连接到一个数据库的用户能够看到 该数据库中所有对象的注释。对于数据库、角色、表空间这类共享对象， 注释被全局存储，因此连接到集簇中任何数据库的任何用户可以看到共 享对象的所有注释。因此，不要在注释中放置有安全性风险的信息。

示例

将评论附加到表 mytable ：

COMMENT ON TABLE mytable IS 'This is my table.';

再次删除它：

COMMENT ON TABLE mytable IS NULL;

更多示例：

COMMENT ON ACCESS METHOD rtree IS 'R-Tree access method';
COMMENT ON AGGREGATE my_aggregate (double precision) IS 'Computes sample variance';
COMMENT ON CAST (text AS int4) IS 'Allow casts from text to int4';
COMMENT ON COLLATION "fr_CA" IS 'Canadian French';
COMMENT ON COLUMN my_table.my_column IS 'Employee ID number';
COMMENT ON CONVERSION my_conv IS 'Conversion to UTF8';
COMMENT ON CONSTRAINT bar_col_cons ON bar IS 'Constrains column col';
COMMENT ON CONSTRAINT dom_col_constr ON DOMAIN dom IS 'Constrains col of domain';
COMMENT ON DATABASE my_database IS 'Development Database';
COMMENT ON DOMAIN my_domain IS 'Email Address Domain';
COMMENT ON EXTENSION hstore IS 'implements the hstore data type';
COMMENT ON FOREIGN DATA WRAPPER mywrapper IS 'my foreign data wrapper';
COMMENT ON FOREIGN TABLE my_foreign_table IS 'Employee Information in other database';
COMMENT ON FUNCTION my_function (timestamp) IS 'Returns Roman Numeral';
COMMENT ON INDEX my_index IS 'Enforces uniqueness on employee ID';
COMMENT ON LANGUAGE plpython IS 'Python support for stored procedures';
COMMENT ON LARGE OBJECT 346344 IS 'Planning document';
COMMENT ON MATERIALIZED VIEW my_matview IS 'Summary of order history';
COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two texts';
COMMENT ON OPERATOR - (NONE, integer) IS 'Unary minus';
COMMENT ON OPERATOR CLASS int4ops USING btree IS '4 byte integer operators for btrees';
COMMENT ON OPERATOR FAMILY integer_ops USING btree IS 'all integer operators for btrees';
COMMENT ON POLICY my_policy ON mytable IS 'Filter rows by users';
COMMENT ON PROCEDURE my_proc (integer, integer) IS 'Runs a report';
COMMENT ON ROLE my_role IS 'Administration group for finance tables';
COMMENT ON RULE my_rule ON my_table IS 'Logs updates of employee records';
COMMENT ON SCHEMA my_schema IS 'Departmental data';
COMMENT ON SEQUENCE my_sequence IS 'Used to generate primary keys';
COMMENT ON SERVER myserver IS 'my foreign server';
COMMENT ON STATISTICS my_statistics IS 'Improves planner row estimations';
COMMENT ON TABLE my_schema.my_table IS 'Employee Information';
COMMENT ON TABLESPACE my_tablespace IS 'Tablespace for indexes';
COMMENT ON TEXT SEARCH CONFIGURATION my_config IS 'Special word filtering';
COMMENT ON TEXT SEARCH DICTIONARY swedish IS 'Snowball stemmer for Swedish language';
COMMENT ON TEXT SEARCH PARSER my_parser IS 'Splits text into words';
COMMENT ON TEXT SEARCH TEMPLATE snowball IS 'Snowball stemmer';
COMMENT ON TRANSFORM FOR hstore LANGUAGE plpythonu IS 'Transform between hstore and Python dict';
COMMENT ON TRIGGER my_trigger ON my_table IS 'Used for RI';
COMMENT ON TYPE complex IS 'Complex number data type';
COMMENT ON VIEW my_view IS 'View of departmental costs';