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Problem Description
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Consider I have the following table structures with approx no. of records in each.

Employee Table
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emp_id:
name :
dept_id:

#Approx no. of rows in the table: 1 million

Department Table
---------------------
dept_id:
dept_name:

#Approx no. of rows in the table: 1 Hundred

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Target Result: is to get the employee name who's id is '100' and the department name he belongs to.
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Ideal Query : Consider it as COMPLEX QUERY
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select emp.name,dept.name
from employee emp, department dept
where
emp.dept_id = dept.dept_id
and
emp.emp_id = '100';

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Optimized Independent Queries : Consider it as SIMPLE QUERIES
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Now i want to split the above query in to two independent queries.

Query #1

select emp.name
from employee emp
where emp.id = '100';

:: Returns one row as emp.id is unique.

Query #2

select dept.dept_id, dept.name
from department dept

:: Returns 100 rows as there are only 100 rows.

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Need Your Suggestions Here
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If you compare the COMPLEX QUERY against SIMPLE QUERIES, i prefer to use SIMPLE QUERIES, get the results
and compare department id against two results programmatically and then get the final result. I know the database
query engines will do similar query optimization like dividing COMPLEX QUERY to SIMPLE QUERIES and run them
in some specific order to get results faster.

Now is it possible to get the exact sub queries which the database query engine (ANY database query engine) generates
out of complex select query? I mean i don't want to do the splitting manually but i still need those sub-queries.

Can any one help me out please?

have you ever heard of joins?

the database will almost always perform a single join query much faster than two separate queries

Yes,I know about joins.
But for some other purpose i need those split of queries. Is is possible to get those queries in any way?

What's complex about your COMPLEX QUERY?

Assuming the correct indexes then the COMPLEX QUERY should return results almost instantly. Have you actually tried running the queries and timing them?

Is it school work?