Fetching with a cursor, PL-SQL Programming

Fetching with a Cursor

The FETCH statements retrieve the rows in the result set one at a time. After each and every fetch, the cursor advance to the next row in the result set. An illustration is a shown:

FETCH c1 INTO my_empno, my_ename, my_deptno;

For each column the value returned by the query related with the cursor, there should be a parallel, type-compatible variable in the INTO list. Normally, you use the FETCH statement in the following way:

LOOP

FETCH c1 INTO my_record;

EXIT WHEN c1%NOTFOUND;

-- process data record

END LOOP;

The query can reference the PL/SQL variables within its scope. Though, any variables in the query are evaluated only when the cursor is opened. In the illustration, each retrieved the salary is multiplied by 2, even though the factor is incremented after each fetch:

DECLARE

my_sal emp.sal%TYPE;

my_job emp.job%TYPE;

factor INTEGER := 2;

CURSOR c1 IS SELECT factor*sal FROM emp WHERE job = my_job;

BEGIN

...

OPEN c1; -- here factor equals 2

LOOP

FETCH c1 INTO my_sal;

EXIT WHEN c1%NOTFOUND;

factor := factor + 1; -- does not affect FETCH

END LOOP;

END;

To change the result set or the values of the variables in the query, you should close and reopen the cursor with the input variables set to their new values.

Though, you can use a different INTO list on separate fetches with similar cursor. Each fetch retrieves another row and assigns values to the target variables, as the illustration shows:

DECLARE

CURSOR c1 IS SELECT ename FROM emp;

name1 emp.ename%TYPE;

name2 emp.ename%TYPE;

name3 emp.ename%TYPE;

BEGIN

OPEN c1;

FETCH c1 INTO name1; -- this fetches first row

FETCH c1 INTO name2; -- this fetches second row

FETCH c1 INTO name3; -- this fetches third row

...

CLOSE c1;

END;

Posted Date: 10/4/2012 3:54:01 AM | Location : United States







Related Discussions:- Fetching with a cursor, Assignment Help, Ask Question on Fetching with a cursor, Get Answer, Expert's Help, Fetching with a cursor Discussions

Write discussion on Fetching with a cursor
Your posts are moderated
Related Questions
Expression: This is a randomly complex combination of constants, variables, literals, operators, & function calls. The simplest expression consists of a single variable. If th

Using Aggregation on Nested Tables Example is the most direct translation of its counterpart in the theory book that can be obtained in SQL but it is so over-elaborate that no

Application to Export Excel Data to MSSQL Server table I am having a table available in excel format and features the subsequent: - Some text is in Arabic (e.g. UTF-8 encodin

Parameter and Keyword Description: select_item: This select_item is a value returned by the SELECT statement, and then assigned to the equivalent variable or field in the

Creating a SQL file 1. Open a new file in Notepad++ and save it to the location c:\mysql\bin, with the name lab8script.sql (the file extension should be .sql ). Add a MySQL co

I need SQL to infopath data connection Project Description: Want data retrieval connection from SQL to SharePoint infopath Skills required are Sharepoint, SQL

Inner Join We have learned how to retrieve data from one table by using SELECT statement. But, as we have learned, normalized relational databases mean the data is spread betw

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

Hi,am developing a library system and relating all the table is somehow complex,could you kindly assist me

Type versus Representation Confusion in SQL This describes how a value might have two or more distinct representations. For example, user-defined type POINT might have a decla