Oracle cursor for updating in oracle Women who want webcam free c2c

Posted by / 09-Oct-2020 02:38

Oracle cursor for updating in oracle

Developers often tell me that they write a cursor FOR loop to fetch a single row. Oracle Database does so much of the work for you, saving several lines of code and several minutes of typing.But there’s a problem with using a cursor FOR loop for a single-row fetch: the resulting code is very misleading. However, from a best practices standpoint, writing code that is transparent in purpose and easy to read and understand is most important.Instead, consider a “next page” paradigm, in which the page has a preset maximum number of rows and the query that retrieves the next set of rows includes a WHERE clause that specifies that range of rows.BULK COLLECT with LIMIT when you don’t know the upper limit.This reuse is important, because it will make optimizing the SQL statements in your application much easier.In particular, you will be able to take advantage of Oracle Database 11’s function result cache feature more quickly and smoothly.The resulting performance improvement can be an order of magnitude or greater.

First, because Oracle Database automatically optimizes cursor FOR loops to execute similarly to BULK COLLECT, as long as the body of your loop does not push changes back to the database, your “read-only” cursor FOR loop will almost always suffice.

If you are fetching very large numbers of rows (10s of 1000s and more), it is possible that switching to FETCH-BULK COLLECT and a high LIMIT value will make your code somewhat faster. Next, if you’re writing a “one-off” script, or a program that is run only occasionally and is not in the critical path of operations, you may want to choose the simplicity and readability of the cursor FOR loop over the incremental improvement in performance (and additional complexity of code) that BULK COLLECT offers.

Use an implicit SELECT INTO for single-row fetches.

Even when the query itself is automatically optimized to return 100 rows with each fetch, the INSERT or UPDATE will happen on a row-by-row basis.

This is one of the worst performance “anti-patterns” in database programming.

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END process_employee; The implicit SELECT INTO offers the most-efficient means of returning that single row of information to your PL/SQL program.

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