How to drop unnamed unique constraint in ORACLE

The following statement drops the unique key on the email column of the employees table:

ALTER TABLE employees DROP UNIQUE (email);

The DROP clause in this statement omits the CASCADE clause. Because of this omission, Oracle Database does not drop the unique key if any foreign key references it.

Description of the illustration drop_constraint_clause

Starting secondary namenodes [0.0.0.0] problem

Here is the solution.

Stack overflow

“InRelease: Clearsigned file isn’t valid, got ‘NODATA’ (does the network require authentication?)” when updating package list

http://stackoverflow.com/questions/24487165/inrelease-clearsigned-file-isnt-valid-got-nodata-does-the-network-require

Virtual Box 4.3.6 Guest Additions problem with Ubuntu 14.04

Guest Additions in Oracle Virtual Box 4.3.6 version somehow conflicts with Ubuntu 14.04 LTS.

It says

Warning: unknown version of the X Window System installed.  Not
installing X Window System drivers.

Do not dig in for help on the internet. Just use Oracle Virtual Box 4.3.28.It worked for me.

2014 in review

The WordPress.com stats helper monkeys prepared a 2014 annual report for this blog.

Here’s an excerpt:

A San Francisco cable car holds 60 people. This blog was viewed about 410 times in 2014. If it were a cable car, it would take about 7 trips to carry that many people.

Click here to see the complete report.

Oracle “DROP TABLE”

DROP  TABLE

Use the DROP TABLE statement to move a table or object table to the recycle bin or to remove the table and all its data from the database entirely.

Dropping a table invalidates dependent objects and removes object privileges on the table. Thus if you just want to claim the space, have a look at ” TRUNCATE TABLE”.

SYNTAX

DROP TABLE [ schema. ] table  [ CASCADE CONSTRAINTS ] [ PURGE ] ;

PURGE

Specify PURGE if you want to drop the table and release the space associated with it in a single step. If you specify PURGE, then the database does not place the table and its dependent objects into the recycle bin.

Using this clause is equivalent to first dropping the table and then purging it from the recycle bin.

Shit !!! I dropped “Users” table. What can ı do now ? Hint: “FLASHBACK TABLE”; but that’s for another post.

CASCADE CONSTRAINTS

Specify CASCADE CONSTRAINTS to drop all referential integrity constraints (foreign keys) that refer to primary and unique keys in the dropped table. If you omit this clause, and such referential integrity constraints exist, then the database returns an error and does not drop the table.

 

 

 

“Doğan” Car of the Year

Legendary car of 80’s in Turkiye

http://gecmisgazete.com/haber/-dogan-gene-yilin-otomobili-?tamBoyut

Listing table, view etc. comments in ORACLE

SELECT OWNER,
TABLE_NAME,
COMMENTS
FROM   DBA_TAB_COMMENTS
WHERE  OWNER = :owner
ORDER  BY OWNER,
TABLE_NAME;

Difference between user_objects, all_objects and dba_objects

Difference between those views is;

• USER_OBJECTS shows the current user objects.
• ALL_OBJECTS shows all objects of current and those object which you have rights to access.
• DBA_OBJECTS shows all object of all users .

Lets generalize this valuable information. It is applicable to every user_<blabla>, all_<blabla>, dba_<blabla> views.

I got this information here. But a wise man one said.

“Repeat the real truth wherever it is needed, altough its not revealed by you”

Dont ask me who was this guy. Never saw him.

List locked objects

SELECT VLO.OS_USER_NAME               “OS USERNAME”,
VLO.ORACLE_USERNAME            “DB USER”,
VP.SPID                        “SPID”,
AO.OWNER                       “OWNER”,
AO.OBJECT_NAME                 “OBJECT LOCKED”,
AO.OBJECT_TYPE,
DECODE (VLO.LOCKED_MODE, 1, ‘NO LOCK’,
2, ‘ROW SHARE’,
3, ‘ROW EXCLUSIVE’,
4, ‘SHARE’,
5, ‘SHARE ROW EXCL’,
6, ‘EXCLUSIVE’,
NULL) “MODE OF LOCK”,
VS.STATUS                      “CURRENT STATUS”
FROM   V$LOCKED_OBJECT VLO,
ALL_OBJECTS AO,
V$SESSION VS,
V$PROCESS VP
WHERE  VLO.OBJECT_ID = AO.OBJECT_ID
AND VS.STATUS <> ‘KILLED’
AND VLO.SESSION_ID = VS.SID
AND VS.PADDR = VP.ADDR;