Oracle interview questions

I need interview questions on oracle & C# will anyone help me.

regards

I'm betting you didn't do a search before posting this question.
Because a search would have revealed that C# interview questions are in the .NET area with a link to interview questions for other technologies as well, including Oracle.

[1. To see current user name Sql> show user; 2. Change SQL prompt name SQL> set sqlprompt “Manimara > “ Manimara > 3. Switch to DOS prompt SQL> host 4. How do I eliminate the duplicate rows ? SQL> delete from table_name where rowid not in (select max(rowid) from table group by duplicate_values_field_name); or SQL> delete duplicate_values_field_name dv from table_name ta where rowid <(select min(rowid) from table_name tb where ta.dv=tb.dv); 5. How do I display row number with records? To achive this use rownum pseudocolumn with query, like SQL> SQL> select rownum, ename from emp; 6. Display the records between two range select rownum, empno, ename from emp where rowid in (select rowid from emp where rownum <=&upto minus select rowid from emp where rownum<&Start); Enter value for upto: 10 Enter value for Start: 7 ROWNUM EMPNO ENAME --------- --------- ---------- 1 7782 CLARK 2 7788 SCOTT 3 7839 KING 4 7844 TURNER 7. I know the nvl function only allows the same data type(ie. number or char or date Nvl(comm, 0)), if commission is null then the text “Not Applicable” want to display, instead of blank space. How do I write the query? SQL> select nvl(to_char(comm.),'NA') from emp; NVL(TO_CHAR(COMM),'NA') ----------------------- NA 300 500 NA 1400 NA NA 8. Oracle cursor : Implicit & Explicit cursors Oracle uses work areas called private SQL areas to create SQL statements. PL/SQL construct to identify each and every work are used, is called as Cursor. For SQL queries returning a single row, PL/SQL declares all implicit cursors. For queries that returning more than one row, the cursor needs to be explicitly declared. 9. Explicit Cursor attributes There are four cursor attributes used in Oracle cursor_name%Found, cursor_name%NOTFOUND, cursor_name%ROWCOUNT, cursor_name%ISOPEN 10. Implicit Cursor attributes Same as explicit cursor but prefixed by the word SQL SQL%Found, SQL%NOTFOUND, SQL%ROWCOUNT, SQL%ISOPEN Tips : 1. Here SQL%ISOPEN is false, because oracle automatically closed the implicit cursor after executing SQL statements. : 2. All are Boolean attributes. 11. Find out nth highest salary from emp table SELECT DISTINCT (a.sal) FROM EMP A WHERE &N = (SELECT COUNT (DISTINCT (b.sal)) FROM EMP B WHERE a.sal<=b.sal); Enter value for n: 2 SAL --------- 3700 12. To view installed Oracle version information SQL> select banner from v$version; 13. Display the number value in Words SQL> select sal, (to_char(to_date(sal,'j'), 'jsp')) from emp; the output like, SQL> select sal "Salary ", (' Rs. '|| (to_char(to_date(sal,'j'), 'Jsp'))|| ' only.')) "Sal in Words" from emp 14. Display Odd/ Even number of records Odd number of records: select * from emp where (rowid,1) in (select rowid, mod(rownum,2) from emp); Even number of records: select * from emp where (rowid,0) in (select rowid, mod(rownum,2) from emp) 15. Which date function returns number value? months_between 16. Any three PL/SQL Exceptions? Too_many_rows, No_Data_Found, Value_Error, Zero_Error, Others 17. What are PL/SQL Cursor Exceptions? Cursor_Already_Open, Invalid_Cursor 18. Other way to replace query result null value with a text SQL> Set NULL ‘N/A’ to reset SQL> Set NULL ‘’ 19. What are the more common pseudo-columns? SYSDATE, USER , UID, CURVAL, NEXTVAL, ROWID, ROWNUM 20. What is the output of SIGN function? 1 for positive value, 0 for Zero, -1 for Negative value. 21. What is the maximum number of triggers, can apply to a single table? 12 triggers. 22. How would you determine the time zone under which a database was operating? select DBTIMEZONE from dual;23. Explain the use of setting GLOBAL_NAMES equal to TRUE. Setting GLOBAL_NAMES dictates how you might connect to a database. This variable is either TRUE or FALSE and if it is set to TRUE it enforces database links to have the same name as the remote database to which they are linking. 24. What command would you use to encrypt a PL/SQL application? WRAP 25. Explain the use of table functions. Table functions are designed to return a set of rows through PL/SQL logic but are intended to be used as a normal table or view in a SQL statement. They are also used to pipeline information in an ETL process. 26. Name three advisory statistics you can collect. Buffer Cache Advice, Segment Level Statistics, & Timed Statistics 27. Where in the Oracle directory tree structure are audit traces placed? In unix $ORACLE_HOME/rdbms/audit, in Windows the event viewer 28. Explain materialized views and how they are used. Materialized views are objects that are reduced sets of information that have been summarized, grouped, or aggregated from base tables. They are typically used in data warehouse or decision support systems. 29. When a user process fails, what background process cleans up after it? PMON 30. What background process refreshes materialized views? The Job Queue Processes. 31. How would you determine what sessions are connected and what resources they are waiting for? Use of V$SESSION and V$SESSION_WAIT 32. Describe what redo logs are. Redo logs are logical and physical structures that are designed to hold all the changes made to a database and are intended to aid in the recovery of a database. 33. How would you force a log switch? ALTER SYSTEM SWITCH LOGFILE;34. Give two methods you could use to determine what DDL changes have been made. You could use Logminer or Streams 35. What does coalescing a tablespace do? Coalescing is only valid for dictionary-managed tablespaces and de-fragments space by combining neighboring free extents into large single extents. 36. What is the difference between a TEMPORARY tablespace and a PERMANENT tablespace? A temporary tablespace is used for temporary objects such as sort structures while permanent tablespaces are used to store those objects meant to be used as the true objects of the database. 37. Name a tablespace automatically created when you create a database. The SYSTEM tablespace. 38. When creating a user, what permissions must you grant to allow them to connect to the database? Grant the CONNECT to the user. 39. How do you add a data file to a tablespace? ALTER TABLESPACE <tablespace_name> ADD DATAFILE <datafile_name> SIZE <size>40. How do you resize a data file? ALTER DATABASE DATAFILE <datafile_name> RESIZE <new_size>;41. What view would you use to look at the size of a data file? DBA_DATA_FILES42. What view would you use to determine free space in a tablespace? DBA_FREE_SPACE43. How would you determine who has added a row to a table? Turn on fine grain auditing for the table. 44. How can you rebuild an index? ALTER INDEX <index_name> REBUILD;45. Explain what partitioning is and what its benefit is. Partitioning is a method of taking large tables and indexes and splitting them into smaller, more manageable pieces. 46. You have just compiled a PL/SQL package but got errors, how would you view the errors? SHOW ERRORS47. How can you gather statistics on a table? The ANALYZE command. 48. How can you enable a trace for a session? Use the DBMS_SESSION.SET_SQL_TRACE or Use ALTER SESSION SET SQL_TRACE = TRUE; 49. Name two files used for network connection to a database. TNSNAMES.ORA and SQLNET.ORA