Oracle comment添加注释

Oracle 的 COMMENT 语句可以给一个列、表、视图或快照添加一个最多 2K 字节的注释。注释被存储在数据字典中，并且可以通过数据字典视图 DBA_COL_COMMENTS （列的注释）和 DBA_TAB_COMMENTS （表的注释）查看 COMMENTS 列。 COMMENT 语句的语法：

COMMENT ON TABLE tb | COLUMN tb.cols IS 'text';

其中， tb 是表的名字， cols 是表中列的名字， text 是注释的文本。可以用设置注释为空串（ '' ）的办法从数据库中删除一个注释，例如：

COMMENT ON TABLE employees IS '';
COMMENT ON TABLE HR.employees IS 'Employee Information';
COMMENT ON COLUMN HR.employees.FIRST_NAME IS 'Employee FIRST_NAME';

对于 SYS 用户下的表，只有拥有 ALTER 权限的普通用户才可以对其进行 COMMENT 操作。对于普通用户下的表，拥有“ COMMENT ANY TABLE ”或 ALTER 权限的普通用户都可以执行 COMMENT 操作。示例如下：

SYS@test18c> create table t as select * from dual;Table created.SYS@test18c> create user lhr33 identified by lhr;User created.SYS@test18c> grant create session to lhr33;Grant succeeded.SYS@test18c> GRANT SELECT ON sys.t to lhr33;Grant succeeded.SYS@test18c> conn lhr33/lhr
Connected.
LHR33@test18c>
LHR33@test18c> select * from sys.t;DU
--
XLHR33@test18c> comment on column sys.t.dummy is 'aa';
comment on column sys.t.dummy is 'aa'*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> comment on table sys.t is 'aa';
comment on table sys.t is 'aa'*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> conn / as sysdba
Connected.
SYS@test18c> grant alter on sys.t to lhr33;Grant succeeded.SYS@test18c> conn lhr33/lhr
Connected.LHR33@test18c>
LHR33@test18c> comment on table sys.t is 'aa';Comment created.LHR33@test18c> comment on column sys.t.dummy is 'aa';Comment created.LHR33@test18c> conn / as sysdba
Connected.
SYS@test18c> revoke alter on sys.t  from lhr33;Revoke succeeded.SYS@test18c> conn lhr33/lhr
Connected.
LHR33@test18c> comment on column sys.t.dummy is 'aa';
comment on column sys.t.dummy is 'aa'*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> conn / as sysdba
Connected.
SYS@test18c> grant COMMENT ANY TABLE   to lhr33;Grant succeeded.SYS@test18c> conn lhr33/lhr
Connected.
LHR33@test18c> comment on column sys.t.dummy is 'aa';
comment on column sys.t.dummy is 'aa'*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> comment on table sys.t is 'aa';
comment on table sys.t is 'aa'*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> conn / as sysdba
Connected.
SYS@test18c> grant alter on sys.t to lhr33;Grant succeeded.SYS@test18c> conn lhr33/lhr
Connected.
LHR33@test18c> comment on table sys.t is 'aa';Comment created.

对于普通用户下的表，拥有 “ COMMENT ANY TABLE ”或 ALTER 权限的用户都可以执行 COMMENT 操作：

LHR33@test18c> conn lhr/lhr
Connected.
LHR@test18c> create table bb as select * from dual;Table created.LHR@test18c> conn lhr33/lhr
Connected.
LHR33@test18c>  comment on table lhr.bb is 'bb';Comment created.LHR33@test18c> select * from lhr.bb;
select * from lhr.bb*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> conn / as sysdba
Connected.
SYS@test18c> revoke COMMENT ANY TABLE from lhr33;Revoke succeeded.SYS@test18c> conn lhr33/lhr
Connected.
LHR33@test18c>  comment on table lhr.bb is 'bb';comment on table lhr.bb is 'bb'*
ERROR at line 1:
ORA-00942: table or view does not existLHR33@test18c> conn / as sysdba
Connected.
SYS@test18c> grant select on lhr.bb to lhr33;Grant succeeded.SYS@test18c> conn lhr33/lhr
Connected.
LHR33@test18c>  comment on table lhr.bb is 'bb';comment on table lhr.bb is 'bb'*
ERROR at line 1:
ORA-01031: insufficient privilegesLHR33@test18c> conn lhr/lhr
Connected.
LHR@test18c> grant alter on lhr.bb to lhr33;Grant succeeded.LHR@test18c> conn lhr33/lhr
Connected.
LHR33@test18c>  comment on table lhr.bb is 'bb';Comment created.

视图 DBA_COL_COMMENTS 和 DBA_TAB_COMMENTS 在做开发时非常实用，举例如下：

create table SCOTT.G_PROD_USER_CONF
(func_type     VARCHAR2(20) not null,func_sub_type VARCHAR2(20) not null,userid        VARCHAR2(20) not null,username      VARCHAR2(50) not null,sendtype      VARCHAR2(20) not null,email_address VARCHAR2(500)
);
-- Add comments to the table
comment on table SCOTT.G_PROD_USER_CONF is '系统功能人员配置';
-- Add comments to the columns
comment on column SCOTT.G_PROD_USER_CONF.func_type  is '功能类型 ';
comment on column SCOTT.G_PROD_USER_CONF.func_sub_type  is '功能子类型 1=收件人 2=抄送人 3=密送人 4=发件人';
comment on column SCOTT.G_PROD_USER_CONF.userid is '员工工号';
comment on column SCOTT.G_PROD_USER_CONF.username is '员工姓名';
comment on column SCOTT.G_PROD_USER_CONF.sendtype is '发送类型1：短信2：邮件3：通知公告';
comment on column SCOTT.G_PROD_USER_CONF.email_address is '电子邮箱';
-- Grant/Revoke object privileges
grant select, insert, update, delete, references, alter, index on SCOTT.G_PROD_USER_CONF to PUBLIC;
通过视图可以查询出一些有用的SQL语句：
SELECT * FROM DBA_TAB_COMMENTS D WHERE D.TABLE_NAME = 'G_PROD_USER_CONF';
SELECT 'A.' || D.COLUMN_NAME || ',','--' || D.COMMENTS,'P_' || DTC.COLUMN_NAME || ' ' || DTC.DATA_TYPE || ',','P_' || DTC.COLUMN_NAME || ' ' || DTC.DATA_TYPE || ',' || ' --' ||D.COMMENTS 入参,'A.' || D.COLUMN_NAME || ' ' || D.COLUMN_NAME || ',' || '--' ||D.COMMENTS 查询,'P_' || D.COLUMN_NAME || ',' || '--' || D.COMMENTS 插入,'A.' || D.COLUMN_NAME || '=' || 'P_' || DTC.COLUMN_NAME || ', --' ||D.COMMENTS 更新,D.COLUMN_NAME || ', --' || D.COMMENTS,D.COMMENTS,DECODE(DTC.DATA_TYPE, 'DATE', 'DATE', '') DATA_TYPE,'--' || D.COMMENTS || CHR(10) ||' v_sql := v_sql || fun_sqlparam(p_' || D.COLUMN_NAME ||', '' and A.' || D.COLUMN_NAME || (CASEWHEN DTC.DATA_TYPE = 'VARCHAR2' THENQ'[ = ''{0}'' '); ]'ELSEQ'[ = {0} ');]'END) WHERE条件FROM DBA_COL_COMMENTS D, DBA_TAB_COLS DTCWHERE D.TABLE_NAME = DTC.TABLE_NAMEAND D.COLUMN_NAME = DTC.COLUMN_NAMEAND D.OWNER = DTC.OWNERAND D.TABLE_NAME = 'G_PROD_USER_CONF'AND D.OWNER = 'SCOTT'ORDER BY DTC.COLUMN_ID;

返回结果，只列举部分：

COMMENT

COMMENT ON COLUMN employees.job_id IS 'abbreviated job title';

COMMENT ON COLUMN employees.job_id IS ' ';

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