Thursday, 22 August 2013
Thursday, 25 April 2013
Tuesday, 9 April 2013
SQL Tutorial
To Learn SQL refer below link
http://www.tutorialspoint.com/sql/index.htm
Important Queries
http://www.tutorialspoint.com/sql/index.htm
Important Queries
Date / Time related queries
Get the first day of the month
Quickly returns the first day of current month. Instead of current month you want to find first day of month where a date falls, replace SYSDATE with any date column/value.
SELECTTRUNC (SYSDATE,'MONTH')"First day of current month"FROMDUAL;Get the last day of the month
This query is similar to above but returns last day of current month. One thing worth noting is that it automatically takes care of leap year. So if you have 29 days in Feb, it will return 29/2. Also similar to above query replace SYSDATE with any other date column/value to find last day of that particular month.
SELECTTRUNC (LAST_DAY (SYSDATE))"Last day of current month"FROMDUAL;Get the first day of the Year
First day of year is always 1-Jan. This query can be use in stored procedure where you quickly want first day of year for some calculation.
SELECTTRUNC (SYSDATE,'YEAR')"Year First Day"FROMDUAL;Get the last day of the year
Similar to above query. Instead of first day this query returns last day of current year.
SELECTADD_MONTHS (TRUNC (SYSDATE,'YEAR'), 12) - 1"Year Last Day"FROMDUALGet number of days in current month
Now this is useful. This query returns number of days in current month. You can change SYSDATE with any date/value to know number of days in that month.
SELECTCAST(TO_CHAR (LAST_DAY (SYSDATE),'dd')ASINT) number_of_daysFROMDUAL;Get number of days left in current month
Below query calculates number of days left in current month.
SELECTSYSDATE,LAST_DAY (SYSDATE)"Last",LAST_DAY (SYSDATE) - SYSDATE"Days left"FROMDUAL;Get number of days between two dates
Use this query to get difference between two dates in number of days.
Use second query if you need to find number of days since some specific date. In this example number of days since any employee is hired.SELECTROUND ( (MONTHS_BETWEEN ('01-Feb-2014','01-Mar-2012') * 30), 0)num_of_daysFROMDUAL;ORSELECTTRUNC(sysdate) - TRUNC(e.hire_date)FROMemployees;Display each months start and end date upto last month of the year
This clever query displays start date and end date of each month in current year. You might want to use this for certain types of calculations.
SELECTADD_MONTHS (TRUNC (SYSDATE,'MONTH'), i) start_date,TRUNC (LAST_DAY (ADD_MONTHS (SYSDATE, i))) end_dateFROMXMLTABLE ('for $i in 0 to xs:int(D) return $i'PASSING XMLELEMENT (d,FLOOR (MONTHS_BETWEEN (ADD_MONTHS (TRUNC (SYSDATE,'YEAR') - 1, 12),SYSDATE)))COLUMNS iINTEGERPATH'.');Get number of seconds passed since today (since 00:00 hr)
SELECT(SYSDATE - TRUNC (SYSDATE)) * 24 * 60 * 60 num_of_sec_since_morningFROMDUAL;Get number of seconds left today (till 23:59:59 hr)
SELECT(TRUNC (SYSDATE+1) - SYSDATE) * 24 * 60 * 60 num_of_sec_leftFROMDUAL;Data dictionary queries
Check if a table exists in the current database schema
A simple query that can be used to check if a table exists before you create it. This way you can make your create table script rerunnable. Just replace table_name with actual table you want to check. This query will check if table exists for current user (from where the query is executed).
SELECTtable_nameFROMuser_tablesWHEREtable_name ='TABLE_NAME';Check if a column exists in a table
Simple query to check if a particular column exists in table. Useful when you tries to add new column in table using ALTER TABLE statement, you might wanna check if column already exists before adding one.
SELECTcolumn_nameASFOUNDFROMuser_tab_colsWHEREtable_name ='TABLE_NAME'ANDcolumn_name ='COLUMN_NAME';Showing the table structure
This query gives you the DDL statement for any table. Notice we have pass ‘TABLE’ as first parameter. This query can be generalized to get DDL statement of any database object. For example to get DDL for a view just replace first argument with ‘VIEW’ and second with your view name and so.
SELECTDBMS_METADATA.get_ddl ('TABLE','TABLE_NAME','USER_NAME')FROMDUAL;Getting current schema
Yet another query to get current schema name.
SELECTSYS_CONTEXT ('userenv','current_schema')FROMDUAL;Changing current schema
Yet another query to change the current schema. Useful when your script is expected to run under certain user but is actually executed by other user. It is always safe to set the current user to what your script expects.
ALTERSESSIONSETCURRENT_SCHEMA = new_schema;Database administration queries
Database version information
Returns the Oracle database version.
SELECT*FROMv$version;Database default information
Some system default information.
SELECTusername,profile,default_tablespace,temporary_tablespaceFROMdba_users;Database Character Set information
Display the character set information of database.
SELECT*FROMnls_database_parameters;Get Oracle version
SELECTVALUEFROMv$system_parameterWHEREname='compatible';Store data case sensitive but to index it case insensitive
Now this ones tricky. Sometime you might querying database on some value independent of case. In your query you might do UPPER(..) = UPPER(..) on both sides to make it case insensitive. Now in such cases, you might want to make your index case insensitive so that they don’t occupy more space. Feel free to experiment with this one.
CREATETABLEtab (col1 VARCHAR2 (10));CREATEINDEXidx1ONtab (UPPER(col1));ANALYZETABLEa COMPUTESTATISTICS;Resizing Tablespace without adding datafile
Yet another DDL query to resize table space.
ALTERDATABASEDATAFILE'/work/oradata/STARTST/STAR02D.dbf'resize 2000M;Checking autoextend on/off for Tablespaces
Query to check if autoextend is on or off for a given tablespace.
SELECTSUBSTR (file_name, 1, 50), AUTOEXTENSIBLEFROMdba_data_files;(OR)SELECTtablespace_name, AUTOEXTENSIBLEFROMdba_data_files;Adding datafile to a tablespace
Query to add datafile in a tablespace.
ALTERTABLESPACE data01ADDDATAFILE'/work/oradata/STARTST/data01.dbf'SIZE1000M AUTOEXTENDOFF;Increasing datafile size
Yet another query to increase the datafile size of a given datafile.
ALTERDATABASEDATAFILE'/u01/app/Test_data_01.dbf'RESIZE 2G;Find the Actual size of a Database
Gives the actual database size in GB.
SELECTSUM(bytes) / 1024 / 1024 / 1024ASGBFROMdba_data_files;Find the size occupied by Data in a Database or Database usage details
Gives the size occupied by data in this database.
SELECTSUM(bytes) / 1024 / 1024 / 1024ASGBFROMdba_segments;Find the size of the SCHEMA/USER
Give the size of user in MBs.
SELECTSUM(bytes / 1024 / 1024)"size"FROMdba_segmentsWHEREowner ='&owner';Last SQL fired by the User on Database
This query will display last SQL query fired by each user in this database. Notice how this query display last SQL per each session.
SELECTS.USERNAME ||'('|| s.sid ||')-'|| s.osuser UNAME,s.program ||'-'|| s.terminal ||'('|| s.machine ||')'PROG,s.sid ||'/'|| s.serial# sid,s.status"Status",p.spid,sql_text sqltextFROMv$sqltext_with_newlines t, V$SESSION s, v$process pWHEREt.address = s.sql_addressANDp.addr = s.paddr(+)ANDt.hash_value = s.sql_hash_valueORDERBYs.sid, t.piece;Performance related queries
CPU usage of the USER
Displays CPU usage for each User. Useful to understand database load by user.
SELECTss.username, se.SID, VALUE / 100 cpu_usage_secondsFROMv$session ss, v$sesstat se, v$statname snWHEREse.STATISTIC# = sn.STATISTIC#ANDNAMELIKE'%CPU used by this session%'ANDse.SID = ss.SIDANDss.status ='ACTIVE'ANDss.usernameISNOTNULLORDERBYVALUEDESC;Long Query progress in database
Show the progress of long running queries.
SELECTa.sid,a.serial#,b.username,opname OPERATION,target OBJECT,TRUNC (elapsed_seconds, 5)"ET (s)",TO_CHAR (start_time,'HH24:MI:SS') start_time,ROUND ( (sofar / totalwork) * 100, 2)"COMPLETE (%)"FROMv$session_longops a, v$session bWHEREa.sid = b.sidANDb.usernameNOTIN('SYS','SYSTEM')ANDtotalwork > 0ORDERBYelapsed_seconds;Get current session id, process id, client process id?
This is for those who wants to do some voodoo magic using process ids and session ids.
SELECTb.sid,b.serial#,a.spid processid,b.process clientpidFROMv$process a, v$session bWHEREa.addr = b.paddrANDb.audsid = USERENV ('sessionid');- V$SESSION.SID AND V$SESSION.SERIAL# is database process id
- V$PROCESS.SPID is shadow process id on this database server
- V$SESSION.PROCESS is client PROCESS ID, ON windows it IS : separated THE FIRST # IS THE PROCESS ID ON THE client AND 2nd one IS THE THREAD id.
Last SQL Fired from particular Schema or Table:
SELECTCREATED,TIMESTAMP, last_ddl_timeFROMall_objectsWHEREOWNER ='MYSCHEMA'ANDOBJECT_TYPE ='TABLE'ANDOBJECT_NAME ='EMPLOYEE_TABLE';Find Top 10 SQL by reads per execution
SELECT*FROM(SELECTROWNUM,SUBSTR (a.sql_text, 1, 200) sql_text,TRUNC (a.disk_reads / DECODE (a.executions, 0, 1, a.executions))reads_per_execution,a.buffer_gets,a.disk_reads,a.executions,a.sorts,a.addressFROMv$sqlarea aORDERBY3DESC)WHEREROWNUM < 10;Oracle SQL query over the view that shows actual Oracle connections.
SELECTosuser,username,machine,programFROMv$sessionORDERBYosuser;Oracle SQL query that show the opened connections group by the program that opens the connection.
SELECTprogram application,COUNT(program) Numero_SesionesFROMv$sessionGROUPBYprogramORDERBYNumero_SesionesDESC;Oracle SQL query that shows Oracle users connected and the sessions number for user
SELECTusername Usuario_Oracle,COUNT(username) Numero_SesionesFROMv$sessionGROUPBYusernameORDERBYNumero_SesionesDESC;Get number of objects per owner
SELECTowner,COUNT(owner) number_of_objectsFROMdba_objectsGROUPBYownerORDERBYnumber_of_objectsDESC;Utility / Math related queries
Convert number to words
More info: Converting number into words in Oracle
Output:SELECTTO_CHAR (TO_DATE (1526,'j'),'jsp')FROMDUAL;
one thousand five hundred twenty-sixFind string in package source code
Below query will search for string ‘FOO_SOMETHING’ in all package source. This query comes handy when you want to find a particular procedure or function call from all the source code.
--search a string foo_something in package source codeSELECT*FROMdba_sourceWHEREUPPER(text)LIKE'%FOO_SOMETHING%'ANDowner ='USER_NAME';Convert Comma Separated Values into Table
The query can come quite handy when you have comma separated data string that you need to convert into table so that you can use other SQL queries like IN or NOT IN. Here we are converting ‘AA,BB,CC,DD,EE,FF’ string to table containing AA, BB, CC etc. as each row. Once you have this table you can join it with other table to quickly do some useful stuffs.
WITHcsvAS(SELECT'AA,BB,CC,DD,EE,FF'AScsvdataFROMDUAL)SELECTREGEXP_SUBSTR (csv.csvdata,'[^,]+', 1,LEVEL) pivot_charFROMDUAL, csvCONNECTBYREGEXP_SUBSTR (csv.csvdata,'[^,]+', 1,LEVEL)ISNOTNULL;Find the last record from a table
This ones straight forward. Use this when your table does not have primary key or you cannot be sure if record having max primary key is the latest one.
SELECT*FROMemployeesWHEREROWIDIN(SELECTMAX(ROWID)FROMemployees);(OR)SELECT*FROMemployeesMINUSSELECT*FROMemployeesWHEREROWNUM < (SELECTCOUNT(*)FROMemployees);Row Data Multiplication in Oracle
This query use some tricky math functions to multiply values from each row. Read below article for more details.
More info: Row Data Multiplication In Oracle
WITHtblAS(SELECT-2 numFROMDUALUNIONSELECT-3 numFROMDUALUNIONSELECT-4 numFROMDUAL),sign_valAS(SELECTCASEMOD (COUNT(*), 2)WHEN0THEN1ELSE-1ENDvalFROMtblWHEREnum < 0)SELECTEXP (SUM(LN (ABS(num)))) * valFROMtbl, sign_valGROUPBYval;Generating Random Data In Oracle
You might want to generate some random data to quickly insert in table for testing. Below query help you do that. Read this article for more details.
More info: Random Data in Oracle
SELECTLEVELempl_id,MOD (ROWNUM, 50000) dept_id,TRUNC (DBMS_RANDOM.VALUE (1000, 500000), 2) salary,DECODE (ROUND (DBMS_RANDOM.VALUE (1, 2)), 1,'M', 2,'F') gender,TO_DATE (ROUND (DBMS_RANDOM.VALUE (1, 28))||'-'|| ROUND (DBMS_RANDOM.VALUE (1, 12))||'-'|| ROUND (DBMS_RANDOM.VALUE (1900, 2010)),'DD-MM-YYYY')dob,DBMS_RANDOM.STRING ('x', DBMS_RANDOM.VALUE (20, 50)) addressFROMDUALCONNECTBYLEVEL< 10000;Random number generator in Oracle
Plain old random number generator in Oracle. This ones generate a random number between 0 and 100. Change the multiplier to number that you want to set limit for.
--generate random number between 0 and 100SELECTROUND (DBMS_RANDOM.VALUE () * 100) + 1ASrandom_numFROMDUAL;Check if table contains any data
This one can be written in multiple ways. You can create count(*) on a table to know number of rows. But this query is more efficient given the fact that we are only interested in knowing if table has any data.
SELECT1FROMTABLE_NAMEWHEREROWNUM = 1;
Friday, 22 February 2013
Calculating Differnece between 2 dates in minutes
select round((second_date - first_date) * (60 * 24),2) as time_in_minutes
from
(
select
to_date('02/21/2013 01:30:00 PM','mm/dd/yyyy hh:mi:ss am') as first_date
,to_date('02/22/2013 01:30:00 PM','mm/dd/yyyy HH:MI:SS AM') as second_date
from
dual
) dual
from
(
select
to_date('02/21/2013 01:30:00 PM','mm/dd/yyyy hh:mi:ss am') as first_date
,to_date('02/22/2013 01:30:00 PM','mm/dd/yyyy HH:MI:SS AM') as second_date
from
dual
) dual
Wednesday, 20 February 2013
Installing Windows7/Windows8 From Removable Media
Below are the steps you must follow when you want to install windows7 from USB stick:
After completing all the process your removable media will look like this
Prerequisites:1.USB Flash Drive (Minimum 4GB)
2.Windows 7 or Windows 8 installation files.
Step1:Plug-in your USB flash drive to USB port and move all the contents from USB drive to a safe location on your system.
Reason:Here we need to format the drive,as a result you may loose your data which is currently present in your removable media
Step2: Open Command Prompt with admin rights. Use any of the below methods to open Command Prompt with admin rights.
-------Type cmd in Start menu search box and hit Ctrl+ Shift+ Enter.
or
--------Press windows logo+R and then type cmd and hit enter (Note :You must be logged in as ADMIN )
Step3:Type DISKPART and hit enter
Step4:Type LIST DISK command and note down the Disk number (ex: Disk 1) of your USB flash drive. In the below screenshot my Flash Drive Disk no is Disk 1.
Step5: Next type all the below commands one by one. Here I assume that your disk drive no is “Disk 1”.If you have Disk 2 as your USB flash drive then use Disk 2.Refer the Step4 to confirm it.
So below are the commands you need to type and execute one by one:
SELECT DISK 1
CLEAN
CREATE PARTITION PRIMARY
SELECT PARTITION 1
ACTIVE
FORMAT FS=NTFS
(Format process may take few seconds)
ASSIGN
EXIT
Complete Screenshot is shown below:
Step6:Open another command promt
Step7:Insert your Windows7 media into your Optical Drive
and check the drive letter of the DVD drive. In this guide I will assume that your DVD drive letter is “D” and USB drive letter is “H” (open my computer to know about it).
Step8: Type D: and hit enter
Step9:Type CD BOOT and hit enter
Where “D” is your DVD drive letter and Boot is the Directory name
Step10: Type BOOTSECT.EXE /NT60 H:
---->To update the USB drive with BOOTMGR compatible code.
Now Your removable Media is ready to Boot
Step10: Copy your Windows 7 or Windows 8 DVD contents to the USB flash drive.
Step11:Your USB drive is ready to boot and install Windows 7 or Windows 8. Only thing you need to change the boot priority at the BIOS to USB from the HDD or CD Drive
Sunday, 10 February 2013
Creating EO without WHO column in OAF
As per java standards, any class which extends an abstract class, must implement the abstract methods of the parent class or should be declared abstract itslef.
So Your child class must implement theses methods which is show as below
First:import theses package
import oracle.jbo.domain.Date;
import oracle.jbo.domain.Number;
Then implement these metods
public void setCreationDate(Date date){}
public void setCreatedBy(Number number){}
public void setLastUpdateDate(Date date){}
public void setLastUpdatedBy(Number number){}
public void setLastUpdateLogin(Number number){}
Thursday, 7 February 2013
All System Date Function
A. Get the Current System Date and Time
SELECT SYSDATETIME()
,SYSDATETIMEOFFSET()
,SYSUTCDATETIME()
,CURRENT_TIMESTAMP
,GETDATE()
,GETUTCDATE();
/* Returned:
SYSDATETIME() 2007-04-30 13:10:02.0474381
SYSDATETIMEOFFSET()2007-04-30 13:10:02.0474381 -07:00
SYSUTCDATETIME() 2007-04-30 20:10:02.0474381
CURRENT_TIMESTAMP 2007-04-30 13:10:02.047
GETDATE() 2007-04-30 13:10:02.047
GETUTCDATE() 2007-04-30 20:10:02.047
B. Get the Current System Date
SELECT CONVERT (date, SYSDATETIME())
,CONVERT (date, SYSDATETIMEOFFSET())
,CONVERT (date, SYSUTCDATETIME())
,CONVERT (date, CURRENT_TIMESTAMP)
,CONVERT (date, GETDATE())
,CONVERT (date, GETUTCDATE());
/* Returned
SYSDATETIME() 2007-05-03
SYSDATETIMEOFFSET()2007-05-03
SYSUTCDATETIME() 2007-05-04
CURRENT_TIMESTAMP 2007-05-03
GETDATE() 2007-05-03
GETUTCDATE() 2007-05-04
*/
C. Get the Current System Time
SELECT CONVERT (time, SYSDATETIME())
,CONVERT (time, SYSDATETIMEOFFSET())
,CONVERT (time, SYSUTCDATETIME())
,CONVERT (time, CURRENT_TIMESTAMP)
,CONVERT (time, GETDATE())
,CONVERT (time, GETUTCDATE());
/* Returned
SYSDATETIME() 13:18:45.3490361
SYSDATETIMEOFFSET()13:18:45.3490361
SYSUTCDATETIME() 20:18:45.3490361
CURRENT_TIMESTAMP 13:18:45.3470000
GETDATE() 13:18:45.3470000
GETUTCDATE() 20:18:45.3470000
*/
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