Rownum - sql pseudocolumns, PL-SQL Programming

Assignment Help:

ROWNUM

The ROWNUM returns a number representing the order in which a row was selected from the table. The first row selected has a ROWNUM of 1; the second row has a ROWNUM of 2, and so on. If the SELECT statement involves an ORDER BY clause, then the ROWNUMs are assigned to the retrieved rows before the sort is complete.

You can use the ROWNUM in an UPDATE statement to assign exclusive values to each row in a table. You can also use ROWNUM in the WHERE clause of a SELECT statement to the limit the number of rows retrieved, as shown:

DECLARE

CURSOR c1 IS SELECT empno, sal FROM emp

WHERE sal > 2000 AND ROWNUM < 10; -- returns 10 rows

The value of ROWNUM increase only whenever a row is retrieved, so the only significant use of ROWNUM in a WHERE clause is

... WHERE ROWNUM < constant;


Related Discussions:- Rownum - sql pseudocolumns

Pl/sql conditional control: if statements, Pl/sql Conditional Control: IF s...

Pl/sql Conditional Control: IF statements Frequently, it is necessary to take the alternative actions depending on the circumstances. The IF statement execute a series of statem

Primary key, PRIMARY KEY: PRIMARY KEY  indicates that the table is sub...

PRIMARY KEY: PRIMARY KEY  indicates that the table is subject to a key constraint, in this case declaring that no two rows in the table assigned to ENROLMENT can ever have the

Multiset types - sql, Multiset types - SQL An SQL multiset is what in ...

Multiset types - SQL An SQL multiset is what in mathematics is also known as a bag-something like a set except that the same element can appear more than once. The body of an

Defining records, Defining and Declaring Records To create records, yo...

Defining and Declaring Records To create records, you have to define a RECORD type, and then declare records of that type. You may also define RECORD types in the declarative

Rollback behavior - bulk bind performance improvement, Rollback Behavior ...

Rollback Behavior When a FORALL statement fails, the database changes are rolled back to an implicit savepoint marked before each of the SQL statement execution. The Changes t

Using forall and bulk collect - bulk bind performance, Using FORALL and BUL...

Using FORALL and BULK COLLECT Together You can unite the BULK COLLECT clause with the FORALL statement, in that case, the SQL engine bulk-binds column values incrementally. In

Using the collection methods, Using the Collection Methods The collecti...

Using the Collection Methods The collection methods below help to generalize the code and make collections easier to use and also make your applications easier to maintain:

Role of abstraction in pl/sql, Role of Abstraction in pl/sql: The abst...

Role of Abstraction in pl/sql: The abstraction is a high-level description or model of a real-world entity. The Abstractions keep our daily lives convenient. They help us ca

Between operator-comparison operators, BETWEEN Operator The operator BET...

BETWEEN Operator The operator BETWEEN, tests whether the value lies in a specified series. That means "greater than or equivalent to low value and less than or equivalent to hig

Creating and destroying base tables, Creating and Destroying Base Tables: ...

Creating and Destroying Base Tables: Example shows an SQL command to create the base table counterpart of the ENROLMENT variable Example  Creating a base table. CREATE T

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd