What is a pseudo column. Give some examples?

More DBA job interview questions and answers at http://dba.fyicenter.com/Interview-Questions/

(Continued from previous question...)

What is a pseudo column. Give some examples?

Information such as row numbers and row descriptions are automatically stored by Oracle and is directly accessible, ie. not through tables. This information is contained within pseudo columns. These pseudo columns can be retrieved in queries. These pseudo columns can be included in queries which select data from tables.

Available Pseudo Columns
· ROWNUM - row number. Order number in which a row value is retrieved.
· ROWID - physical row (memory or disk address) location, ie. unique row identification.
· SYSDATE - system or today’s date.
· UID - user identification number indicating the current user.
· USER - name of currently logged in user.

(Continued on next question...)

Other Job Interview Questions

• What is content of DBC file and why its important ?
• What is dev60cgi and f60cgi ?
• How to check if Oracle application 11i System is Rapid Clone enabled ?
• Which two tables created at start of application Patch and drops at end of Patch ?
• What is US directory in $AD_TOP or under various product TOP's .
• What is content of DBC file and why its important ?
• What are different modes of forms in which you can start Forms Server and which one is default ?
• What WHERE CURRENT OF clause does in a cursor?
• How to check if application 11i System is Autoconfig enabled ?
• What is ADSPLICE UTILITY ?
• More...