Oracle Create Table AS和表注释以及列注释

Question

是否可以将另一个表创建为CREATE TABLE AS并保留列的注释？

CREATE TABLE TABLE1_COPY AS SELECT * FROM TABLE1;

上一条语句不包括列的注释。因此，TABLE1_COPY保留无列注释。是否也在使用USER_COL_COMMENTS在新创建的表上重现相同注释的唯一方法？

Answer 1

至于DMBS_METADATA.GET_DDL，除非我缺少一些属性，否则它似乎不会产生COMMENT ON COLUMN语句。

一种方法是结合使用dbms_metadata.get_dependent_ddl和dbms_metadata.get_ddl

这是使用SQL plus创建的示例：

SQL> set long 1000000

SQL> create table t (x number);

Table created.

SQL> comment on column T.X IS 'this is the column comment';

Comment created.

SQL> comment on table T IS 'this is the table comment';

Comment created.

SQL> SELECT dbms_metadata.get_ddl( 'TABLE', 'T' ) || ' ' ||
  2         dbms_metadata.get_dependent_ddl( 'COMMENT', 'T', USER ) the_ddl
  3  FROM dual
  4  /

THE_DDL
--------------------------------------------------------------------------------

  CREATE TABLE "SCOTT"."T"
   (    "X" NUMBER
   ) SEGMENT CREATION DEFERRED
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
  TABLESPACE "USERS"

   COMMENT ON COLUMN "SCOTT"."T"."X" IS 'this is the column comment'

   COMMENT ON TABLE "SCOTT"."T"  IS 'this is the table comment'