SQL PRO AND ORACLE SQL URGENT HELP

Question

Can any one help me out here withe these questions:
Pro C Qusetions:
1.     What are the SQLCA and SQLDA ?
2.     What is a mutating table ?
3.     What are indicator variables and how are they used ?
4.     What are the components of the Oracle VARCHAR type and how should such a structure be loaded into a C Char type ?
5.     Why would you use the ‘ALTER SESSION’ command in conjunction with the tkprof program and what is the purpose of each step ?
ORACLE SQL QUESTIONS:
1.0     How would you move data from one Oracle database to another Oracle database?
2.0     How would you import data into an Oracle database from another DBMS or flat file?
3.0     What is an Outer Join and how does the output differ from a simple join?
4.0     What is the difference between the conditional expressions IN and EXISTS ? In what circumstances would you USE EACH.
5.0      You cannot create a unique index on a table due to duplicate values. Describe how you find the offending row and subsequently delete it.

Answer 1

1. What are the SQLCA and SQLDA ?
SQLCA = SQL Communications area: stores status variable and error message text. manual reference
SQLDA = SQL Descriptor Area - stores information about bind variables. manual reference
2. What is a mutating table ?
A table that is being modified and that you are trying to select from. Usually encountered in a before insert/update trigger when trying to select from the table that is being inserted/updated, which causes the dreaded ORA-04091 error.
3. What are indicator variables and how are they used ?
Used in Pro*C to tell if the table column contains the value NULL.
4. What are the components of the Oracle VARCHAR type and how should such a structure be loaded into a C Char type ?
varchar2 is a null-terminated string. Use Pro*C extended type VARCHAR. Manual Reference
5. Why would you use the "ALTER SESSION" command in conjunction with the tkprof program and what is the purpose of each step ?
Use alter session to set tracing on for your session:
alter session set sql_trace = true ;
this will create a trace file in the user dump destination
(select value from v$parameter where name = 'user_dump_dest'). Use tkprof to format the trace file.
1.0 How would you move data from one Oracle database to another Oracle database?
Export / Import Oracle utility, Database link and INSERT ... SELECT ..., Database link and COPY command, save to flat file and use SQL*Loader, transportable tablespaces, database "cloning" by copying database files over to a new server and creating a new instance based on those files. List of manuals look up CREATE DATABASE LINK in the SQL Reference, COPY command in the SQL*Plus reference, Export/Import or SQL*Loader in the Utilities manual.
2.0 How would you import data into an Oracle database from another DBMS or flat file?
SQL*Loader Oracle Utility
3.0 What is an Outer Join and how does the output differ from a simple join?
An example is worth 1000 words.
SQL> select * from emp ;
   EMP_NO EMP_NAME     DEPT_NO
        1 SMITH              1
        2 JONES              1
        3 BROWN              2
        4 BOND               5
SQL> select * from dept ;
  DEPT_NO DEPT_NAME
        1 SALES
        2 MARKETING
SQL> -- inner or "ordinary" join
SQL> select a.emp_name, b.dept_name
  2  from emp a, dept b
  3  where a.dept_no = b.dept_no ;
EMP_NAME   DEPT_NAME
SMITH      SALES
JONES      SALES
BROWN      MARKETING
SQL> -- outer join
SQL> select a.emp_name, b.dept_name
  2  from emp a, dept b
  3  where a.dept_no = b.dept_no (+) ;
EMP_NAME   DEPT_NAME
SMITH      SALES
JONES      SALES
BROWN      MARKETING
BOND5.0 You cannot create a unique index on a table due to duplicate values. Describe how you find the offending row and subsequently delete it.
Using exceptions clause of enable constraint
ALTER TABLE employees
ENABLE VALIDATE CONSTRAINT emp_manager_fk
EXCEPTIONS INTO exceptions ;
Find rowids in exceptions table and use those rowids to delete the "bad" data. See SQL reference on alter table for more details.