记录一下Orale获取表DDL语句的过程-CFANZ编程社区

正文：

工作上数据库搭建测试环境只需要部分表进行测试不要求环境完全一样，给出让导出一两张表的表结构在新库建立即可。

这里我用到 dbms_metadata.get_ddl 这个函数简单记录一下：

首先查询建表DDL语句,返回的是一个clob字段,给出的建表SQL：

select dbms_metadata.get_ddl('TABLE','DB_OPERATE_RECORD','ERUPT') from dual;


  CREATE TABLE "ERUPT"."DB_OPERATE_RECORD" 
   (	"OPERATE_ID" NUMBER(30,0) NOT NULL ENABLE, 
	"TABLE_NAME" VARCHAR2(200) NOT NULL ENABLE, 
	"ORIGINAL_DATA" CLOB, 
	"OPERATE_SCRIPT" CLOB, 
	"ROLLBACK_SCRIPT" CLOB, 
	"REMARKS" VARCHAR2(100), 
	"CREATE_TIME" DATE DEFAULT sysdate, 
	"SOURCE_ID" VARCHAR2(100), 
	"REQUEST_IP" VARCHAR2(100), 
	"ROLLBACK_FLAG" NUMBER DEFAULT 0, 
	"ROLLBACK_TIME" DATE DEFAULT null, 
	 CONSTRAINT "DB_OPERATE_ID" PRIMARY KEY ("OPERATE_ID")
  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "ERUPT"  ENABLE
   ) SEGMENT CREATION IMMEDIATE 
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "ERUPT" 
 LOB ("ORIGINAL_DATA") STORE AS BASICFILE (
  TABLESPACE "ERUPT" ENABLE STORAGE IN ROW CHUNK 8192 RETENTION 
  NOCACHE LOGGING 
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)) 
 LOB ("OPERATE_SCRIPT") STORE AS BASICFILE (
  TABLESPACE "ERUPT" ENABLE STORAGE IN ROW CHUNK 8192 RETENTION 
  NOCACHE LOGGING 
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)) 
 LOB ("ROLLBACK_SCRIPT") STORE AS BASICFILE (
  TABLESPACE "ERUPT" ENABLE STORAGE IN ROW CHUNK 8192 RETENTION 
  NOCACHE LOGGING 
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT))

这里我们发现给出的建表ddl语句没有字段注释，我们需要使用另一个函数来获取字段注释并comment,具体操作如下

SELECT DISTINCT DBMS_LOB.substr(DBMS_METADATA.get_dependent_ddl('COMMENT',
              'DB_OPERATE_RECORD')) as table_comment
                FROM (SELECT distinct table_name
                        FROM user_col_comments
                       WHERE comments IS NOT NULL);

执行此语句我们会得到字段COMMENT的执行语句，如下：


   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."OPERATE_ID" IS '操作记录ID'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."TABLE_NAME" IS '表名称'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."ORIGINAL_DATA" IS '原始数据'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."OPERATE_SCRIPT" IS '操作脚本'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."ROLLBACK_SCRIPT" IS '数据还原脚本'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."REMARKS" IS '备注'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."CREATE_TIME" IS '创建时间'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."SOURCE_ID" IS '数据源ID'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."REQUEST_IP" IS '请求IP'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."ROLLBACK_FLAG" IS '回滚恢复标记'
 
   COMMENT ON COLUMN "ERUPT"."DB_OPERATE_RECORD"."ROLLBACK_TIME" IS '回滚恢复时间'

直接在建表后执行语句即可还原原表字段注释了。

扩展：

dbms_metadata.get_ddl函数的语法：

SELECT DBMS_METADATA.GET_DDL(OBJECT_TYPE, NAME, SCHEMA) FROM DUAL

上述传入的参数含义如下：

参数	释义
OBJECT_TYPE	对象的类型,如TABLE、INDEX、FUNTION等
NAME	对象名，如表名，索引名，函数名等
SCHEMA	对象所在schema，默认为当前用户所在schema
VERSION	可选参数，对象原数据的版本
MODEL	可选参数，原数据的类型默认为Oracle
TRANSFORM	可选参数

该函数返回的是CLOB数据。

下面是函数定义（可以看到相关的参数）：

-- GET_DDL:     Return the metadata for a single object as DDL.
--      This interface is meant for casual browsing (e.g., from SQLPlus)
--      vs. the programmatic OPEN / FETCH / CLOSE interfaces above.
-- PARAMETERS:
--      object_type     - The type of object to be retrieved.
--      name            - Name of the object.
--      schema          - Schema containing the object.  Defaults to
--                        the caller's schema.
--      version         - The version of the objects' metadata.
--      model           - The object model for the metadata.
--      transform       - XSL-T transform to be applied.
-- RETURNS:     Metadata for the object transformed to DDL as a CLOB.

  FUNCTION get_ddl (
                object_type     IN  VARCHAR2,
                name            IN  VARCHAR2,
                schema          IN  VARCHAR2 DEFAULT NULL,
                version         IN  VARCHAR2 DEFAULT 'COMPATIBLE',
                model           IN  VARCHAR2 DEFAULT 'ORACLE',
                transform       IN  VARCHAR2 DEFAULT 'DDL')
        RETURN CLOB;

下面给出一些其他的DDL查询方法：

--获得某个schema下所有的表、索引、视图、存储过程、函数的DDL
SELECT DBMS_METADATA.GET_DDL('TABLE',u.table_name,u.owner) FROM DBA_TABLES u;
SELECT DBMS_METADATA.GET_DDL('VIEW',u.view_name,u.owner) FROM DBA_VIEWS u;
SELECT DBMS_METADATA.GET_DDL('INDEX',u.index_name,u.owner) FROM DBA_INDEXES u;
SELECT DBMS_METADATA.GET_DDL('PROCEDURE',u.object_name, u.owner,) FROM DBA_OBJECTS u WHERE u.object_type = 'PROCEDURE';
SELECT DBMS_METADATA.GET_DDL('FUNCTION',u.object_name, u.owner,) FROM DBA_OBJECTS u WHERE u.object_type = 'FUNCTION';

--获得某个表空间的DDL
SELECT DBMS_METADATA.GET_DDL('TABLESPACE','TABLES_NAME') FROM DUAL;
--获得所有表空间的DDL
SELECT DBMS_METADATA.GET_DDL('TABLESPACE', TS.tablespace_name) FROM DBA_TABLESPACES TS;

--获得单个用户的DDL
SELECT DBMS_METADATA.GET_DDL('USER','EPAY_USER') FROM DUAL;
--获得所有用户的DDL
SELECT DBMS_METADATA.GET_DDL('USER',U.username) FROM DBA_USERS U;