Plsql what is it

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By closing this banner, scrolling this page, clicking a link or continuing to browse otherwise, you agree to our Privacy Policy. Popular Course in this category. Course Price View Course. Free Data Science Course. Login details for this Free course will be emailed to you. Email ID. Because stored subprograms run in the database server, a single invocation over the network can start a large job.

This division of work reduces network traffic and improves response times. Stored subprograms are cached and shared among users, which lowers memory requirements and invocation overhead. For more information about subprograms, see "Subprograms". The shared memory facilities of the shared server let Oracle Database support thousands of concurrent users on a single node. For further scalability, you can use Oracle Connection Manager to multiplex network connections.

Any number of applications can use the subprograms, and you can change the subprograms without affecting the applications that invoke them. Developers often use CGI scripts to produce web pages dynamically, but such scripts are often not optimal for accessing the database.

For information about packages, see "Packages". The scripts run when Web clients, such as browsers, request the pages. A script can accept parameters, query or update the database, and then display a customized page showing the results.

During development, PSPs can act like templates, with a static part for page layout and a dynamic part for content.

You can design the layouts using your favorite HTML authoring tools, leaving placeholders for the dynamic content. When finished, you simply load the resulting PSP files into the database as stored subprograms. You can break complex problems into easily understandable subprograms, which you can reuse in multiple applications. You do not have to check every operation to ensure that it succeeded, as in a C program.

These keywords divide the block into a declarative part, an executable part, and an exception-handling part. Only the executable part is required. A block can have a label. For syntax details, see "Block". Declarations are local to the block and cease to exist when the block completes execution, helping to avoid cluttered namespaces for variables and subprograms. Blocks can be nested: Because a block is an executable statement, it can appear in another block wherever an executable statement is allowed.

The interactive tool or program runs the block one time. The block is not stored in the database, and for that reason, it is called an anonymous block even if it has a label. An anonymous block is compiled each time it is loaded into memory, and its compilation has three stages:. As the program runs, the values of variables can change, but the values of constants cannot.

For more information, see "Declarations" and "Assigning Values to Variables". If the subprogram has parameters, their values can differ for each invocation. A function returns a result. For more information, see "External Subprograms". A package is compiled and stored in the database, where many applications can share its contents. You can think of a package as an application. You can specify the event, whether the trigger fires before or after the event, and whether the trigger runs for each event or for each row affected by the event.

Some subprograms in the packages in Table can both accept input and display output, but they cannot accept data directly from the keyboard. Data abstraction lets you work with the essential properties of data without being too involved with details. You can design a data structure first, and then design algorithms that manipulate it. You can use the cursor to retrieve the rows of the result set one at a time.

You can use cursor attributes to get information about the state of the cursor—for example, how many rows the statement has affected so far. For more information about cursors, see "Cursors". A composite variable has internal components, which you can access individually.