SQL Plus Interview Preparation Guide

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Retrieves rows in hierarchical order.e.g. select empno, ename from emp where.

"connect by prior" is clause which is used in hierarchical queries.Example
select ename,empno,mgr,job
from emp
start with job='PRESIDENT'
connect by prior empno=mgr;

ROWID is a pseudo column generated at the run time(during inserting value). Its a hexadecimal value which is unique identification for each record

%IS OPEN,%FOUND,%NOT FOUND,%ROW COUNT

Database Link is a named path through which a remote database can be accessed

Correlated subquery is the subquery, where the subquery has been executed for the every row processed by the parent statement.

Drop Index Indexname

Join is a query which retrieves related columns or rows from multiple tables.Self Join - Joining the table with itself.Equi Join - Joining two tables by equating two common columns.Non-Equi Join - Joining two tables by equating two common columns.Outer Join - Joining two tables in such a way that query can also retrieve rows that do not have corresponding join value in the other table.

JOIN: Return rows when there is at least one match in both tables
LEFT JOIN: Return all rows from the left table, even if there are no matches in the right table
RIGHT JOIN: Return all rows from the right table, even if there are no matches in the left table
FULL JOIN: Return rows when there is a match in one of the tables

CHAR,
VARCHAR2,
NUMBER,
DATE,
RAW,
LONG and
LONG RAW.

select empno||' '||ename from emp;

select replace (column name,',','') from table name.

if a view is update, deleted , or inserted wil the changes be refelected on the base table