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

Create Tables, Hi there, I have the final part of a submission to do, it ...

Hi there, I have the final part of a submission to do, it is a demonstration that takes place tomorrow. I do not have to use previous information, but i have resources that sho

Updating by replacement, Updating by replacement Syntax: UPDAT...

Updating by replacement Syntax: UPDATE ENROLMENT SET Name = 'Ann' WHERE StudentId = SID ('S1'); Note the use of SET, as already noted in connection with direct a

How bulk bind helps improvement in performance?, How Bulk Binds Improve Per...

How Bulk Binds Improve Performance The assigning of values to the PL/SQL variables in SQL statements is known as binding. The binding of the whole collection at once is know

Dbms, DBMS: The answer to this question is of course given in of the t...

DBMS: The answer to this question is of course given in of the theory book. This book is concerned with SQL DBMSs and SQL databases in particular. Soon we will be looking a

Logical connectives - sql, Logical Connectives - SQL SQL's extended t...

Logical Connectives - SQL SQL's extended truth tables in which the symbol, for unknown, appears along with the usual T and F. Negation (NOT, ¬) Conjunction (

Authorisations - privileges, Authorisations - Privileges As relational...

Authorisations - Privileges As relational theory is silent on the issue of authorisation, it offers nothing with which SQL's vast edifice in support of what it calls privilege

Example of using aggregation on nested tables, Example of Using Aggregation...

Example of Using Aggregation on Nested Tables Example: How many students sat each exam WITH C_ER AS (SELECT CourseId, CAST (TABLE (SELECT DISTINCT StudentId, Mark FROM EXAM

Query optimization, 1.( /5 marks) Suppose that a B+-tree index with the sea...

1.( /5 marks) Suppose that a B+-tree index with the search key (dept_name, building) is available on relation department. What would be the best way to handle the following selecti

Extension and and in sql, Extension and AND in SQL The theory book giv...

Extension and AND in SQL The theory book gives the following simple example of relational extension in Tutorial D: EXTEND IS_CALLED ADD ( FirstLetter ( Name ) AS Initial )

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

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