Quick Tip #4

To see what SQL a session is running in the database, find the SPID for that user using sp_who2 and then pass it as an input to the dbcc command.


sp_who2

dbcc inputbuffer (:SPID)

NULL SELF Argument Is Disallowed - Oracle

ORA-30625: method dispatch on NULL SELF argument is disallowed 

Cause: A member method of a type is being invoked with a NULL SELF argument. 
Action: Change the method invocation to pass in a valid self argument.


Well i was trying to parse an XML with multiple namespaces and was using EXISTSNODE function. When traversing between nodes and subnodes i forgot to remove a subnode name and the XPATH formed was incorrect:

    l_xmltype := xmltype (l_doc) ;
    l_index := 1;
    v_count := l_xmltype.existsnode (
    'ns1:NewSubscriptionNotificationRequest/subscriptionInfo/subscriptionKey/subscriptionInfo [' || to_char (l_index
    ) || ']', v_namespaces);
    dbms_output.put_line ('------' || v_count);
    --
    WHILE l_xmltype.existsnode (
    'ns1:NewSubscriptionNotificationRequest/subscriptionInfo [' || TO_CHAR (l_index
    ) || ']', v_namespaces) > 0
    LOOP
        l_value := l_xmltype.extract (
        'ns1:NewSubscriptionNotificationRequest/subscriptionInfo [' || to_char (
        l_index) || ']/duration/text()', v_namespaces) .getstringval () ;
        dbms_output.put_line ('-------------> ' || l_value) ;
        --
        l_index := l_index + 1;

    END LOOP;

This error is same as the evil NULL POINTER EXCEPTION in JAVA....

Just correcting the subnode path (remove subscriptionInfo from EXISTSNODE) to represent right structure helped resolve this problem.

Many thanks to A_Non On XML for his detailed explanation and examples on this blog about XML parsing. I hope he does not mind a well deserved praise.

PLSCOPE_SETTINGS in Oracle

Today i was working on an object creation script and had a trigger for audit columns like date inserted, date updated etc...

I constantly kept getting the error below and on further research found out a workaround from one of the blogs (thank you fellow blogger):


Error report:
ORA-00603: ORACLE server session terminated by fatal error
ORA-00600: internal error code, arguments: [kqlidchg0], [], [], [], [], [], [], [], [], [], [], []
ORA-00604: error occurred at recursive SQL level 1
ORA-00001: unique constraint (SYS.I_PLSCOPE_SIG_IDENTIFIER$) violated
00603. 00000 -  "ORACLE server session terminated by fatal error"
*Cause:    An ORACLE server session is in an unrecoverable state.
*Action:   Login to ORACLE again so a new server session will be created
Failed to resolve object details 

Workaround: ALTER SESSION SET PLSCOPE_SETTINGS = 'IDENTIFIERS:NONE';

By default the value is IDENTIFIERS:ALL 
The database default value is NONE and later found out it was SQL Developer setting.


After altering the session the trigger was compiled without any problems....hope this 
helps.

PL/SQL Compiler Setting in SQL Developer

Google is my friend :)

SYS_CONTEXT in Oracle

I know there is a functions to get user environment details in Oracle along with other valuable information for auditing purposes in your application. But i always tend to forget it, not anymore

SYS_CONTEXT (NAMESPACE, PARAMETER)       <<<< LOOK MA I AM PINK

Example: select sys_context('USERENV', 'HOST') from dual;

SET DEADLOCK_PRIORITY HIGH

Incase you are expecting a DEADLOCK in an environment where your process/job is going to run executing DML statements and you are fully aware that the process take priority over all other processes/jobs, you can set its priority to HIGH.

This specifies the rank/priority of your process higher than any other process when deadlock is detected.

Deadlock priority is set before the TRY block in the procedure.

Hope this helps....

Error: CREATE/ALTER PROCEDURE must be the first statement in a query batch

I had not come across this error before so was a new one for me. 

declare @cmd varchar(200)
set @cmd = 'sp_rename myproc1, myproc'
exec @cmd
GO

create procedure myproc (input_id int)
as
begin
  if input_id = 0
  begin
    print 'i am in begin block #2'
  end
end

The GO indicates end of batch or acts as a batch separator was missing from the script and as a result the error was generated. Once i added the GO statement, the script executed like a happy little monster....

Hope this helps....

DATEADD and DATEDIFF

I always try to remember these functions but for some reason end up going to MSDN to find the actual function name and syntax.

DATEADD (datepart , number , date )
select DATEADD (mm, 1, getdate())

DATEDIFF ( datepart , startdate , enddate )
select DATEDIFF (hh, getdate(), '2013-04-16 00:11:11.00')

Table below is from MSDN, just to you everyone an overview of possible option to use 
with these functions (along with any other DATE functions)

    

   
datepart
   
abbreviations
  
   
year
   
yy,   yyyy
  
   
quarter
   
qq,   q
  
   
month
   
mm,   m
  
   
dayofyear
   
dy,   y
  
   
day
   
dd,   d
  
   
week
   
wk,   ww
  
   
hour
   
hh
  
   
minute
   
mi,   n
  
   
second
   
ss,   s
  
   
millisecond
   
ms
  
   
microsecond
   
mcs
  
   
nanosecond
   
ns
  

Hope this helps and as always good is my friend....

Retrieve table structure over linked server

exec linkedserver.master.dbo.sp_executesql N'use mydb; exec sp_help order_details'

OR


exec linkedserver master.dbo.sp_executesql N'use mydb; SELECT ORDINAL_POSITION, COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, IS_NULLABLE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = ''order_details'''

Hope this helps....