What do the created, last_ddl_time, timestamp fields mean in the user_objects view
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Meaning of created, last_ddl_time, timestamp fields in user_objects view
Created: the creation time of the object
Last_ddl_time: related to the object (not necessarily changing the structure of the object, but also other related, for example, if the object is a table, assigning select permission to the table to other users will also change the value of this field) the execution time of the last ddl operation
Timestamp: the time when the structure of the object changes, such as deleting fields, adding fields, etc.
SQL > conn dasong/dasong
Connected.
SQL > create table t_obj_time
2 (
3 col1 varchar2 (20)
4 col2 varchar2 (20)
5)
Table created.
SQL > col object_name for A20
SQL > alter session set nls_date_format='YYYY-MM-DD HH24:MI:SS'
Session altered.
If the table has just been created and no operation has been done on the table, the values of created, last_ddl_time and timestamp are the same.
SQL > select object_name, created, last_ddl_time, timestamp from user_objects where object_name='T_OBJ_TIME'
OBJECT_NAME CREATED LAST_DDL_TIME TIMESTAMP
T_OBJ_TIME 2012-02-10 08:56:05 2012-02-10 08:56:05 2012-02-10-02-10 purl 08 purl 56 purl 05
SQL > alter table t_obj_time add (col3 varchar2 (30))
Table altered.
-- after adding a field to the table, the values of last_ddl_time and timestamp are updated, and the values of last_ddl_time and timestamp remain the same, but are no longer the same as created
SQL > select object_name, created, last_ddl_time, timestamp from user_objects where object_name='T_OBJ_TIME'
OBJECT_NAME CREATED LAST_DDL_TIME TIMESTAMP
T_OBJ_TIME 2012-02-10 08:56:05 2012-02-10 08:57:23 2012-02-10-02-10 purl 08PUR 57 JV 23
SQL > grant select on t_obj_time to sys
Grant succeeded.
After the select permission of the table is assigned to the sys user, the LAST_DDL_TIME field is updated again, and the values of the three fields are different.
SQL > select object_name, created, last_ddl_time, timestamp from user_objects where object_name='T_OBJ_TIME'
OBJECT_NAME CREATED LAST_DDL_TIME TIMESTAMP
T_OBJ_TIME 2012-02-10 08:56:05 2012-02-10 08:57:49 2012-02-10-02-10 purl 08PUR 57 JV 23
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