This Oracle tutorial explains how to use the Oracle/PLSQL WHERE CURRENT OF declaration with syntax and examples.
Description
If you sketch on updating or deleting information that have been referenced by using a SELECT FOR UPDATE statement, you can use the WHERE CURRENT OF statement.
Syntax
The syntax for the WHERE CURRENT OF assertion in Oracle/PLSQL is either:
UPDATE table_name
SET set_clause
WHERE CURRENT OF cursor_name;OR
DELETE FROM table_name
WHERE CURRENT OF cursor_name;Note
The WHERE CURRENT OF announcement permits you to replace or delete the report that was remaining fetched through the cursor.
Example
Updating using the WHERE CURRENT OF Statement
Here is an instance the place we are updating data the usage of the WHERE CURRENT OF Statement:
CREATE OR REPLACE Function FindCourse
( name_in IN varchar2 )
RETURN number
IS
cnumber number;
CURSOR c1
IS
SELECT course_number
FROM courses_tbl
WHERE course_name = name_in
FOR UPDATE of instructor;
BEGIN
OPEN c1;
FETCH c1 INTO cnumber;
if c1%notfound then
cnumber := 9999;
else
UPDATE courses_tbl
SET instructor = 'SMITH'
WHERE CURRENT OF c1;
COMMIT;
end if;
CLOSE c1;
RETURN cnumber;
END;Deleting using the WHERE CURRENT OF Statement
Here is an example the place we are deleting records using the WHERE CURRENT OF Statement:
CREATE OR REPLACE Function FindCourse
( name_in IN varchar2 )
RETURN number
IS
cnumber number;
CURSOR c1
IS
SELECT course_number
from courses_tbl
where course_name = name_in
FOR UPDATE of instructor;
BEGIN
open c1;
fetch c1 into cnumber;
if c1%notfound then
cnumber := 9999;
else
DELETE FROM courses_tbl
WHERE CURRENT OF c1;
COMMIT;
end if;
close c1;
RETURN cnumber;
END;