https://blog.csdn.net/DaisyLoveZly/article/details/77503502
oracle comment on的用法 
 oracle中用comment on命令给表或字段加以说明,语法如下: 
 COMMENT ON 
 { TABLE [ schema. ] 
 { table | view } 
 | COLUMN [ schema. ] 
 { table. | view. | materialized_view. } column 
 | OPERATOR [ schema. ] operator 
 | INDEXTYPE [ schema. ] indextype 
 | MATERIALIZED VIEW materialized_view 
 } 
 IS ‘text’ ;
用法如下: 
 1.对表的说明 
 comment on table table_name is ‘comments_on_tab_information’;
2.对表中列的说明 
 comment on column table.column_name is ‘comments_on_col_information’;
3.查看表的说明 
 SQL> select * from user_tab_comments where TABLE_NAME=’EMPLOYEES’;
TABLE_NAME TABLE_TYPE COMMENTS
EMPLOYEES TABLE 员工表
SQL> select * from user_tab_comments where comments is not null;
TABLE_NAME TABLE_TYPE COMMENTS
EMPLOYEES TABLE 员工表
4.查看表中列的说明 
 SQL> select * from user_col_comments where TABLE_NAME=’EMPLOYEES’;
TABLE_NAME COLUMN_NAME COMMENTS
EMPLOYEES EMPLOYEE_ID 
 EMPLOYEES MANAGER_ID 
 EMPLOYEES FIRST_NAME 
 EMPLOYEES LAST_NAME 
 EMPLOYEES TITLE 
 EMPLOYEES SALARY 员工薪水
SQL> select * from user_col_comments where comments is not null;
TABLE_NAME COLUMN_NAME COMMENTS
EMPLOYEES SALARY 员工薪水
5.我们也可以从下面这些视图中查看表级和列级说明: 
 ALL_COL_COMMENTS 
 USER_COL_COMMENTS 
 ALL_TAB_COMMENTS 
 USER_TAB_COMMENTS 
6.删除表级说明,也就是将其置为空 
 SQL> comment on table employees is ”; 
 Comment added
SQL> select * from user_tab_comments where TABLE_NAME=’EMPLOYEES’;
TABLE_NAME TABLE_TYPE COMMENTS
EMPLOYEES TABLE
7.删除列级说明,也是将其置为空 
 SQL> comment on column employees.salary is ”; 
 Comment added
SQL> select * from user_col_comments where TABLE_NAME=’EMPLOYEES’;
TABLE_NAME COLUMN_NAME COMMENTS
EMPLOYEES EMPLOYEE_ID 
 EMPLOYEES MANAGER_ID 
 EMPLOYEES FIRST_NAME 
 EMPLOYEES LAST_NAME 
 EMPLOYEES TITLE 
 EMPLOYEES SALARY 
下面我展示一下项目开发中的实例来做参考
-- Create table
create table F_S_WASH_TASK
(
  task_id         NUMBER(16) not null,
  task_no         VARCHAR2(16) not null,
  equip_categ     VARCHAR2(8),
  task_status     VARCHAR2(8) not null,
  start_date      DATE not null,
  end_date        DATE,
  task_num        NUMBER(15),
  org_no          VARCHAR2(16) not null,
  creator_no      VARCHAR2(16),
  create_date     DATE,
  exec_org_no     VARCHAR2(16),
  team_no         VARCHAR2(16),
  executor_no     VARCHAR2(16),
  parent_task_id  NUMBER,
  priority        VARCHAR2(8) not null,
  remark          VARCHAR2(32),
  finish_remark   VARCHAR2(256),
  wiring_mode     VARCHAR2(8),
  finished_date   DATE,
  real_start_date DATE
)
tablespace MPAC_A
  pctfree 10
  initrans 1
  maxtrans 255
  storage
  (
    initial 64
    next 1
    minextents 1
    maxextents unlimited
  );
-- Add comments to the table 
comment on table F_S_WASH_TASK
  is '清洁分选任务表';
-- Add comments to the columns 
comment on column F_S_WASH_TASK.task_id
  is '唯一标识';
comment on column F_S_WASH_TASK.task_no
  is '清洁分选任务编';
comment on column F_S_WASH_TASK.equip_categ
  is '设备类别,参见计量标准代码:设备类别VW_EQUIP_CATEG';
comment on column F_S_WASH_TASK.task_status
  is '任务状态,01初始、02待分配、03已分配、04执行中、05执行完成、06已完成';
comment on column F_S_WASH_TASK.start_date
  is '任务开始时间';
comment on column F_S_WASH_TASK.end_date
  is '任务结束时间';
comment on column F_S_WASH_TASK.task_num
  is '任务数量';
comment on column F_S_WASH_TASK.org_no
  is '创建单位编号';
comment on column F_S_WASH_TASK.creator_no
  is '创建人';
comment on column F_S_WASH_TASK.create_date
  is '创建时间';
comment on column F_S_WASH_TASK.exec_org_no
  is '执行单位';
comment on column F_S_WASH_TASK.team_no
  is '执行班组';
comment on column F_S_WASH_TASK.executor_no
  is '执行人';
comment on column F_S_WASH_TASK.parent_task_id
  is '父任务标识';
comment on column F_S_WASH_TASK.priority
  is '任务优先级 01一般 02 重要 03紧急';
comment on column F_S_WASH_TASK.remark
  is '备注';
comment on column F_S_WASH_TASK.finish_remark
  is '任务完成备注';
comment on column F_S_WASH_TASK.wiring_mode
  is '接线方式';
comment on column F_S_WASH_TASK.finished_date
  is '任务完成日期';
comment on column F_S_WASH_TASK.real_start_date
  is '任务实际开始时间';
-- Create/Recreate primary, unique and foreign key constraints 
alter table F_S_WASH_TASK
  add constraint PK_F_S_WASH_TASK primary key (TASK_ID)
  using index 
  tablespace MPAC_A
  pctfree 10
  initrans 2
  maxtrans 255
  storage
  (
    initial 64K
    next 1M
    minextents 1
    maxextents unlimited
  );
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