Answer Posted / rajkumar
As database developer, you must have ever written
subqueries in either SQL Server or any other database
platform. This article will describe shortly about types of
subquery.
A subquery is inner query that will be used by outer query.
A subquery could return scalar value or a series of value.
Based on query dependency, a subquery could be self-
contained or correlated one. A self-contained subquery is a
subquery independent from outer query, and correlated
subquery is a subquery that is referencing to a row in
outer query.
Self-contained subquery is easier to debug than correlated
subquery. And it is executed only once whereas correlated
subquery is executed once for each row of outer query.
Sample of self-contained subquery that returns scalar value
is shown below :
Select customerid
From dbo.orders
Where employeeid = (select employeeid from dbo.employees
where lastname = ‘RAJ’);
This query returns customers list whose employee is RAJ.
| Is This Answer Correct ? | 9 Yes | 1 No |
Post New Answer View All Answers
What is a partition function in sql server?
How you can get a list of all the table constraints in a database?
Can you edit the .rdl code associated with a linked report?
my name is sejal I have cleared the sbi clerk exam. I am BCA graduate My favorite subject RDBMS Relational database management system. so please send me rRDBMS related interview questions
What is surrogate key? : sql server analysis services, ssas
Do you know query execution plan?
Can we hide the definition of a stored procedure from a use?
What is the use of toad or sqldbx.?
Can we write ddl in trigger?
What is extended stored procedures?
How many types of dimensions are there and what are they? : sql server analysis services, ssas
Can a synonym name of a table be used instead of a table name in a select statement?
What are system databases into sql server (2005/2008) : sql server database administration
How do you improve the performance of a SQL Azure Database?
Can one drop a column from a table?