Finding out Last DML Activity on a Table

create a function for the DML logging 

create or replace function scn_to_timestamp_safe(p integer) return timestamp is
  e_too_old_scn exception;
  pragma exception_init(e_too_old_scn,-8181);
begin
  return 
     case 
       when p is not null then scn_to_timestamp(p)
       else null
     end;
exception 
  when e_too_old_scn then 
    return null;
end;
/

 now querying the last DML (insert,update,delete) for table and this cant say if 

there was any select query run or not.

 select 
  t.owner||'.'||t.table_name
 ,extractvalue( dbms_xmlgen.getXMLtype(q'[select nvl(scn_to_timestamp_safe

(max(ora_rowscn)),timestamp'0001-01-01 00:00:00') t 

from "]'||t.owner||'"."'||t.table_name||'"')
               ,'/ROWSET/ROW/T'
              ) last_dml
from
  all_tables t
where 
    t.IOT_TYPE is null
and t.TEMPORARY='N'
and t.NESTED='NO';

add owner if you want tables in particular schema at the end of sql.

 >>>     AND OWNER IN ('SCOTT'); 

Find all tables without primarykey in Database

As a  DBA we need to make sure that all the tables in your database are have their uniquesness
 so that the rows are not duplicate and we avoid the redundant data in our databases.

 below is the simple sql that can give you list of tables that don't have any primary key:


SELECT OWNER, table_name
FROM all_tables
MINUS
SELECT OWNER,table_name
FROM all_constraints
WHERE constraint_type = 'P' AND OWNER NOT IN ('sys','system');

you list out all the schemas you want to avoid looking for.

Easiest way to switch between schemas just with a click of button using sqqldeveloper

Easiest way to switch between schemas just with a click of button in sqldeveloper 3.2 or lower versions.This doesnt work with sqldev 4 or higher

General :  
The Schema Select extension for Oracle SQL Developer provides a convenient drop-down list which lets you choose the current schema in a sql worksheet. It also allows you to specify a default schema for newly opened worksheets.

Features:

• Default schema can be specified in connection name
  
  
• Current schema can be selected from a drop-down list
  
  
• Works in Oracle SQL Developer versions 3.0, 2.1 and 1.5
  
  
• Support for Oracle, MySQL and MS Sqlserver databases
  
  
• Easily extendable to support other databases
  
  

This extension was created using Oracle JDeveloper and the IDE Extension SDK.

download it from :

http://javaforge.com/project/schemasel

direct download   >>>
http://javaforge.com/displayDocument/oracle.sqldeveloper.thirdparty.schemaselect.jar?doc_id=80273