Subqueries in oracle database

[Landan]

Hello guys !

Actually,I have some little problem regarding the execution and implementation of subqueries in the oracle database.How is it implemented with the SQL and PL/SQL statement .So please give me some suggestion regarding this issue and it would be appreciated and thanks to view my question.

[Reegan]

The Subqueries :
The subquery is the query within a query.Using SQL statement,you can create and implement your own subquery and can use within the procedures of the database.These queries are covered with the different clause like: SELECT,FROM and WHERE and within that there are so many pseudo columns which can be added to increase the condition based information from database.

[opaper]

Using Subqueries in oracle database :

Probably,the subqueries found between the WHERE clause which is also called the Nested subquery.The example is given below :

select * from all_tables tabs
where tabs.table_name in 	(select col_name.table_name
	 from all_tab_columns cols
	 where cols.column_name = 'specified_conditioning_Column_name ');

[MindSpace]

Sub-Queries with multiple columns :

I am going to show you an example which will give you some result for more than two columns :

SELECT * FROM emp
WHERE (salary,manager) = (1000,41);

This result will return the invalidity error because two columns can't return the required result for two columns but using subquery,we can do it very easily :

SELECT * FROM emp
WHERE (salary,manager) = (SELECT 1000,41 FROM dual);

[Modifier]

Inserting values using subqueries :

You can insert the value in database object and it takes the following form to implement :

SQL> INSERT INTO ( SELECT Emp_id,Emp_name,City FROM Emp_data
              WHERE Mgr_no<30 with check option)
                    VALUES (03, 'Richie', 'Tokyo');