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Why do we need explicit cursor?
An explicit cursor is a named pointer to a private SQL area that stores information for processing a specific query or DML statement—typically, one that returns or affects multiple rows. You can use an explicit cursor to retrieve the rows of a result set one at a time.
What is difference between cursor and FOR loop?
Unlike an implicit cursor, you can reference an explicit cursor or cursor variable by its name. Therefore, an explicit cursor or cursor variable is called a named cursor. The cursor FOR LOOP statement lets you run a SELECT statement and then immediately loop through the rows of the result set.
What is the disadvantage of while loop using cursors?
Disadvantages of using Cursor: This uses much more network bandwidth than the execution of a single SQL statement like SELECT or DELETE etc that makes only one round trip. Repeated network round trips can degrade the speed of the operation using the cursor.
How do SQL cursors work?
Cursors enable manipulation of whole result sets at once. In this scenario, a cursor enables the sequential processing of rows in a result set. In SQL procedures, a cursor makes it possible to define a result set (a set of data rows) and perform complex logic on a row by row basis.
What do you call an explicit cursor in Java?
Unlike an implicit cursor, you can reference an explicit cursor or cursor variable by its name. Therefore, an explicit cursor or cursor variable is called a named cursor. The cursor FOR LOOP statement lets you run a SELECT statement and then immediately loop through the rows of the result set.
What’s the difference between cursors for loop and normal explicit curs?
The rownum optimization is very nice. Here the database KNOWS your intention (i want 1 row). It can do the work better. In the second case — it has to assume you want ALL OF the rows. Hence, it does a ton more work. Very, very informative! Yet again I have learned something new.
What happens if the cursor is not opened in Oracle?
FALSE, if the cursor is not opened in the program. Oracle provides three types of cursors namely SIMPLE LOOP, WHILE LOOP and FOR LOOP. These loops can be used to process multiple rows in the cursor. Here I will modify the same example for each loops to explain how to use loops with cursors.
Do you need to declare cursor in for loop?
When using FOR LOOP you need not declare a record or variables to store the cursor values, need not open, fetch and close the cursor. These functions are accomplished by the FOR LOOP automatically.