SQL ,PLSQL , Unix

The DUAL table was created by  Charles Weiss  of  Oracle Corporation  to provide a table for joining in internal  views : I created the DUAL table as an underlying object in the Oracle Data Dictionary. It was never meant to be seen itself, but instead used inside a view that was expected to be queried. The idea was that you could do a JOIN to the DUAL table and create two rows in the result for every one row in your table. Then, by using GROUP BY, the resulting join could be summarized to show the amount of storage for the DATA extent and for the INDEX extent(s). The name, DUAL, apt for the process of creating a pair of rows from just one. [1] The original DUAL table had two rows in it (hence its name), but subsequently it only had one row. Optimization Beginning with 10g Release 1 Oracle Database have been OPTIMIZED [2]  and the database no longer performs physical or logical IO on the DUAL table even though the DUAL table still actually exists...

Say you are given a task to manipulate a set of 10 million records from a couple of tables. What would you do? Sit and think???!!!! See if the following helps you.. Replicate the tables data into temporary tables Create indexes on the columns you want to manipulate the data Write your query.. Dont ask me what language you are talking!!!! Look at the examples Select count(1) from hugeTable1;--7999900 records Select count(1) from hugeTable2; --9893990 Create table tmp1 as Select * from hugeTable1 where 1=2; insert /*+append*/ into tmp1 select * from hugeTable1; Create table tmp2 as Select * from hugeTable2 Where 1=2; insert /*+append*/ into tmp2 select * from hugeTable2; create index indTmp1 on tmp1(column1,column2); create index indTmp2 on tmp2(column1,column2); Select * from tmp1,tmp2 where tmp1.column1=tmp2.column1 and           tmp1.column2=tmp2.column2;     Should you face any issues, please write to me ( s...

wc - command is used to list all files in  a directory with its records count Prompt>$ wc -l *.txt 10  file1.txt 93  sampleFile.txt 199333 billingData.txt 65  loadData.txt Prompt>$

This was asked in a meeting of following people and the answers are amazing... An Analyst replied  - I need a month time to prepare analysis whether it is possible or the way possible Technical architect replied  -It is not impossible but involves lots of work. Team Lead interrupted  - Google it , you should be able to find it One in the team suggested - It will cause performance issues Developer maintained a silence until everyone calmed down and said.. - Lets make use of data dictionaries - Find out Varchar fields and construct a query - Lets list objects that has the data searched - We will then narrow down our search - It is not time-consuming job yet not a quick one Analyst quickly replied - We know that, but it is not right to do as it will cause unnecessary issues Team Lead                     - Were you not supposed to complete the other assignment? You concentrate on that!!! Technical Archi...

1. file           - Will list the file encoding details           - Read man page for more details 2. pdftohtml         - Utility to convert pdf file to html format 3. iconv -f -t          - to change the file encoding from one format to another  Ex:       iconv -f UTF-16 -t ASCII filename.txt        - Read man page for more supported encoding formats 4.  ls -R | grep -i * *       - List files in subdirectories 5.  last       - To see the list of users who were connected to the system       - It gives you the list with the details logon time, logon ip, user id etc.,

1. Write an SQL statement to delete all duplicate rows in a table.    Give all possible SQL statements that can be used to delete duplicate rows effectively. 2. Consider the following table ID Name Role ManagerId MGR6002 RajeshKumar Manager MGR1001 TM1001 Sridevi Associate MGR6002   TM1002 John Sr.Associate MGR6002 TM1008 Rexan Associate MGR6002   MGR6003 Amruta Manager MGR1001 MGR6004 Justin Manager MGR1001   MGR1001 Ravikumar GPM VCH1001 TM1003 Linton Associate MGR6004   TM1003 Kavitha Sr.Associate MGR6004 TM1005 Sailu Analyst MGR6002   TM1006 Sami Sr.Associate MGR6001       Write an SQL to print employee list hierarchically     Ex output. Rajeshkumar John Rexan Sailu Amruta Justin Linton Kavitha 3. Write the SQL statement to obtain nth salary of employees. 4. Wha...

whoami The command lets you know the user name of the current shell you are at. Example: root@Microknoppix:/home/knoppix# whoami root root@Microknoppix:/home/knoppix# su knoppix knoppix@Microknoppix:~$ whoami knoppix su The su command is used to become another user during a login session. Invoked without a username, su defaults to becoming the superuser. The optional argument - may be used to provide an environment similar to what the user would expect had the user logged in directly. Example : root@Microknoppix:/home/knoppix# su knoppix password: knoppix@Microknoppix:~$ knoppix@Microknoppix:/root$ su - password: root@Microknoppix:~# knoppix@Microknoppix:/root$ su password: root@Microknoppix:~# finger The finger displays information about the system users. Example: root@Microknoppix:~# finger knoppix Login: knoppix Name: Knoppix User Directory: /home/knoppix Shell: /bin...