Answer Posted / asnani_satish@yahoo.com
Minor correction in above answer
Difference between sub-query, correlated query and query as
table
1. Sub-query : the inner query is executed in entirety
before the outer query is executed
eg select * from emp where deptno in (select deptno from dept);
2. Correlated Query: For each record fetched in outer query
corresponding matching records are fetched in sub-query
because of join condition within inner sub-query. Answers
1,2,3 are correct
3. Query as Table: A query can behave as a table
select a.empno,a.sal,a.sal/b.avgsal*100 as percent_avg_sal
from emp a,(select deptno,avg(sal) avgsal from emp group by
deptno) b
where a.deptno=b.deptno;
Here the entire "(select deptno,avg(sal).....)" behaves as
table named "b" containing dept wise average sal. The query
is behaving as a temporary table.
Is This Answer Correct ? | 6 Yes | 9 No |
Post New Answer View All Answers
How many types of relationship are there?
What is primary key sql?
What is anonymous block in sql?
Why do we need a foreign key?
Define union, minus, union all, intersect ?
How do you drop a trigger?
What is a record in pl/sql?
What is execute immediate?
How do you declare a user-defined exception?
What is memory optimized?
Is sql a programming?
Which join is like an inner join?
What is a temporal table?
Explain the difference between sql and mysql.
what are wild cards used in database for pattern matching ? : Sql dba