dbms_metadata.get_ddl获取对象定义脚本

在工作中我们会遇到从数据库中获取某些对象的定义脚本，比如：
PROCEDURE
PACKAGE
PACKAGE BODY
TRIGGER
FUNCTION
TABLE等。
这里就教大家一招获取指定对象的定义语句的方法。
获取HR用户下employees表的结构：
1.查看employees表中有哪些字段：

SQL>desc employees;
名称                                    是否为空? 类型
------------------------------------------------- ----------------------------
EMPLOYEE_ID                     NOT NULL NUMBER(6)
FIRST_NAME                            VARCHAR2(20)
LAST_NAME                      NOT NULL VARCHAR2(25)
EMAIL                         NOT NULL VARCHAR2(25)
PHONE_NUMBER                          VARCHAR2(20)
HIRE_DATE                      NOT NULL DATE
JOB_ID                        NOT NULL VARCHAR2(10)
SALARY                              NUMBER(8,2)
COMMISSION_PCT                         NUMBER(2,2)
MANAGER_ID                            NUMBER(6)
DEPARTMENT_ID                          NUMBER(4)

尝试获取建表语句：
执行效果如下：

SQL> selectDBMS_METADATA.get_ddl('TABLE','EMPLOYEES','HR') from dual;

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------

CREATE TABLE "HR"."EMPLOYEES"
(    "EMPLOYEE_ID"NUMBER(6,0),
"FIRST_NAME"

SQL>

发现显示的不完整，看看配置参数；

SQL> show long
long 80
SQL> set long 9999

重新执行语句

SQL>select DBMS_METADATA.get_ddl('TABLE','EMPLOYEES','HR') from dual;

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------

CREATE TABLE"HR"."EMPLOYEES"
(   "EMPLOYEE_ID" NUMBER(6,0),
"FIRST_NAME" VARCHAR2(20),
"LAST_NAME" VARCHAR2(25)CONSTRAINT "EMP_LA
ST_NAME_NN"NOT NULL ENABLE,
"EMAIL" VARCHAR2(25)CONSTRAINT "EMP_EMAIL_NN" NO
T NULLENABLE,
"PHONE_NUMBER" VARCHAR2(20),
"HIRE_DATE" DATE CONSTRAINT"EMP_HIRE_DATE_NN" NOT N
ULL ENABLE,

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------
"JOB_ID" VARCHAR2(10)CONSTRAINT "EMP_JOB_NN"
NOT NULLENABLE,
"SALARY" NUMBER(8,2),
"COMMISSION_PCT" NUMBER(2,2),
"MANAGER_ID" NUMBER(6,0),
"DEPARTMENT_ID" NUMBER(4,0),
CONSTRAINT "EMP_SALARY_MIN"CHECK (salary > 0
) ENABLE,
CONSTRAINT "EMP_EMAIL_UK"UNIQUE ("EMAIL")
USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS
255 NOLOGGING COMPUTE STATISTICS

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTEN
TS 1MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1BUFFER_
POOLDEFAULT FLASH_CACHE DEFAULT CELL_FL
ASH_CACHEDEFAULT)
TABLESPACE "EXAMPLE"  ENABLE,
CONSTRAINT "EMP_EMP_ID_PK"PRIMARY KEY ("EMPLO
YEE_ID")

USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255NO
LOGGINGCOMPUTE STATISTICS
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS1 MA

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------
XEXTENTS2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GRO
UPS 1BUFFER_POOL DEFAULT FLASH_CACHE DE
FAULTCELL_FLASH_CACHE DEFAULT)
TABLESPACE "EXAMPLE"  ENABLE,
CONSTRAINT "EMP_MANAGER_FK"FOREIGN KEY ("MANAGER_ID"
)
REFERENCES"HR"."EMPLOYEES" ("EMPLOYEE_ID") ENABLE,
CONSTRAINT "EMP_JOB_FK"FOREIGN KEY ("JO
B_ID")
REFERENCES"HR"."JOBS" ("JOB_ID") ENABLE,

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------
CONSTRAINT "EMP_DEPT_FK"FOREIGN KEY ("DEPART
MENT_ID")
REFERENCES"HR"."DEPARTMENTS" ("DEPARTMENT_ID")
ENABLE
) SEGMENT CREATION IMMEDIATE
PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255NOCOMPRESS
NOLOGGING

STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS1
MAXEXTENTS2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1BUFFER_POOL
DEFAULTFLASH_CACHE DEFAULT CELL_FLASH_C

DBMS_METADATA.GET_DDL('TABLE','EMPLOYEES','HR')
--------------------------------------------------------------------------------
ACHEDEFAULT)
TABLESPACE "EXAMPLE"

SQL>

结果就是我们获取的hr.employees的建表语句了。除了表，dbms_metadate.get_ddl还可以获取到触发器，存储过程等的信息。诸如：

select dbms_metadata.get_ddl ('TRIGGER','ACCOUNT','TEST')from dual;

此语句的格式为

select dbms_metadata.get_ddl (‘object_type’,’object_name’,’username’)from dual
;