Answer / dhana

An inline view is a SELECT statement in the FROM-clause of
another SELECT statement. In-line views are commonly used
simplify complex queries by removing join operations and
condensing several separate queries into a single query.
This feature was introduced in Oracle 7.

Answer / dhana

A correlated subquery is a SELECT statement nested inside
another T-SQL statement, which contains a reference to one
or more columns in the outer query. Therefore, the
correlated subquery can be said to be dependent on the outer
query. This is the main difference between a correlated
subquery and just a plain subquery. A plain subquery is not
dependent on the outer query, can be run independently of
the outer query, and will return a result set. A correlated
subquery, since it is dependent on the outer query will
return a syntax errors if it is run by itself.

Answer / madhavi

A subquery is a query (usually enclosed by parentheses)
that appears within another
SQL data manipulation statement. When evaluated, the
subquery provides a value
or set of values to the statement. Often, subqueries are
used in the WHERE clause.
Whereas a subquery is evaluated only once for each table, a
correlated subquery is
evaluated once for each row.
An inline query or inline view is the query whichis in from
clause of select statement

Answer / ramesh reddy veerabhadra

Basically Sub Query is Query within Query. There are different type of SubQuery.

1. Scalar Sub Query

Query that is totally independent from the main query.

select empno, (select count(*) from emp) total_emp
from emp


here the subquery is totally independent of the main query.

2. Corelated Sub Query

The sub query reffers to the main query.

select empno, (select deptname from dept d where e.deptno = d.deptno) deptname
from emp e


3. Inline view

A sub query that is used as a table or view in a SQL

select *
from (select empno, deptname
from emp e, dept d
where e.deptno = d.deptno)
where sal > 100

Answer / ramesh reddy veerabhadra

Subquery is the query in the main select query which runs separately and feeds its output to main query for execution. It runs only once.

SELECT ename, deptno
FROM emp
WHERE deptno = (SELECT deptno
FROM emp
WHERE ename = 'KING');


Corelated sub query uses the values from the main query and runs everytime the main query executes i.e. its simultaneous process.

SELECT ename, deptno, sal
FROM emp x
WHERE sal > (SELECT AVG(sal)
FROM emp
WHERE emp.deptno = x.deptno)
ORDER BY deptno;

Answer / thulasidas kp

An inline view is a SELECT statement in the FROM-clause of
another SELECT statement. In-line views are commonly used
simplify complex queries by removing join operations and
condensing several separate queries into a single query.
This feature was introduced in Oracle 7.

Answer / sharath

Can we use one subquery in another. I have got a situation
like this


select

(select date from t1) date,
((select date from t1 where t1.col1=table.col1)*7) week,
(((select date from t1) where t1.col1=table.col1)*7)
+start_date) transfer

from table;

Somewhat like this. I needed to know whether the first
subquery can be used in the second subquery and the next
subqueries??Or any hints as such just to make the query
faster??

Answer / sharath

Sorry the query posted above is not the one. Please see the
below query.

Can we use one subquery in another. I have got a situation
like this


select

(select date from t1 where t1.col1=table.col1) date,
((select date from t1 where t1.col1=table.col1)*7) week,
(((select date from t1 where t1.col1=table.col1)*7)
+start_date) transfer

from table;

Somewhat like this.
The point is the first subquery is used in second,
third,fourth subqueries. Instead of writing them again, can
we avoid them.

I needed to know whether the first
subquery can be used in the second subquery and the next
subqueries??Or any hints as such just to make the query
faster??

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