What is the full form of PL/SQL

PL/SQL: Procedural Language Extension to the Structured Query Language

PL/SQL is an abbreviation for procedural language extension to the Structured Query Language. This language was developed by Oracle that allows users to perform operations on the database. The primary function of this language was to combine procedural language with the structured query language for the database. The basic unit in PL/SQL is referred to as a block. A block consists of three components. These components are a declarative component, an executable component, and an exception-building component.

Since PL/SQL language allows the user to implement SQL statements using procedural constructs. Moreover, the user can also use the PL/SQL blocks and subprograms that allow the user to merge several SQL statements before delivering those commands to Oracle for executing the statements on the database. This enables Oracle to implement multiple statements simultaneously. Without using PL/SQL, oracle must process each SQL statement one at a time. In a network environment, this can reduce the application's response time as other queries will have to wait to ensure that the statement before them is executed. It also increases the traffic in the network.

Combining procedural language with SQL enables the user to compile the entire block of PL/SQL and store it at once in executable form, reducing the application's response time. The user can build a PL/SQL program stored in a database in a compiled form that can be called anytime using the block's name. It is referred to as stored procedures. It saves users time as they do not have to type the same code again.

The stored procedure in PL/SQL begins as the user implements the INSERT, UPDATE, or DELETE statement issued against a table. The statements that are initially implemented are known as triggers.

Working on PL/SQL

PL/SQL blocks are defined by using SQL keywords such as DECLARE, BEGIN, EXCEPTION, and END. These keywords enable the user to divide the block into three parts. DECLARE keywords define the declarative part of the block, and BEGIN and EXCEPTION define the executable and exception-building components of the block, respectively. In the declarative component of the PL/SQL block, the user needs to define and initialize constants and variables. If the user does not initialize a variable in the declarative part, it will assign a NULL value. It also enables the nest of the blocks and submitting them to iterative tools such as SQL*Plus.

It is developed to calculate and return a single scalar value or groups such as a nested table or VARRAY. The user can also create user-defined functions in addition to those defined by Oracle. Users can implement functions in an SQL statement, whereas procedures cannot.

Examples of Features Provided by PL/SQL

• Some of the features provided by PL/SQL include cursors, embedded PL/SQL, and calling stored procedures. Cursors can be referred to as pointers that point to context area. The user can implement PL/SQL statements to manage the context area. The users can also assign a unique name to the cursor. They can also remain unnamed or anonymous. It is easier to retrieve the cursor if they are assigned a name. It can be both implicit and explicit.
• The cursors defined in the PL/SQL blocks are implicit by default. The cursors can be created in place of an explicit cursor when PL/SQL encounters a SELECT statement that returns a single row or when DML commands such as DELETE and INSERT are implemented on the database.
• Explicit cursors provide better control over the context area. The explicit cursors are implemented with a SELECT query to retrieve single or multiple data records. Both implicit and explicit cursors produce the same output. The primary difference between implicit and explicit cursor lies in the access of the cursor.
• The user can add PL/SQL statements in high-level host languages such as C. Several programming tools, such as Pro*COBOL, read and implement the entire PL/SQL block as a single embedded SQL statement. This makes it possible for the user to use Pl/SQL blocks anywhere in the host program, even when they might want to use an SQL statement instead.
• When embedding PL/SQL blocks in the host program, the user must ensure that all the variables that will be shared with PL/SQL are declared. The next requisition is to bracket the PL/SQL block using EXEC SQL EXECUTE and END-EXEC keywords, as mentioned in the Oracle documentation.
• The user can create stored procedures using PL/SQL. Once the stored procedures are loaded and published, the users can call the procedures, saving them the time and effort to re-type the statements again. The user can establish a connection with Oracle using the Pro*C program.
• Once the complete data is inserted, the program will automatically assign all the data values in the rows in the index by tables associating elements in the host arrays. The program will repeat the procedure and present the data in batches until there is no more data to represent.

Advantages of PL/SQL

1. PL/SQL provides features of structured and procedural query language that make it simpler to implement and execute the queries. It is regarded as a high transaction processing language. It allows the user to directly call the database by implementing external programming language calls.
2. It also enables the user to use elements that belong to procedural languages, such as loops and conditions.
3. It can manage run-time errors, and the user can declare constants and variables to implement the queries.
4. The user can also create procedures, functions, types, and variables.
5. It allows users to create a block of multiple queries that are directly forwarded to the Oracle engine, reducing the traffic and increasing the processing speed.
6. PL/SQL is strongly integrated with SQL, and the integration between procedural programming and structural query language allows the user to use the features of both languages. It can perform SQL data manipulation, provide cursor control and implement SQL pre-defined functions and operators. The user can also create pseudo columns without converting the PL/SQL data types into SQL data types. Moreover, it provides support for both static and dynamic query language.
7. PL/SQL allows the user to forward a group of statements to the database. It reduces the traffic between the application and the database as each transaction is not sent individually. The user can implement PL/SQL on any operating system if it supports the Oracle database.
8. The user can also store PL/SQL queries as subprograms, increasing the scalability and allowing central access processing on the server. The memory functions of the shared server enable the database to support concurrent operations on the database. This means that multiple users can access the database through a single node.
9. It only allows the user to maintain a single copy of the subprogram on the database server instead of using several copies on every system. This makes it easier to manage nodes. Several programs use the subprograms as it allows users to modify the applications that implement them.
10. It also allows the user to implement applications that can create web pages by using the database directly. It allows the user to develop the database that is present on the web.
11. PL/SQL Server pages also enable the user to create webpages and provide an alternative to coding a stored subprogram that develops the HTML code line by line.
12. The user can use PL/SQL server pages as templates while developing web applications. It makes building layouts and writing PL/SQL scripts to develop content easier.

Features Provided by PL/SQL

Some of the features provided by PL/SQL are as follows:

1. It enables the user to use several data types in the query.
2. It also provides features of object-oriented programming.
3. It can also perform error checking in the system.
4. It is firmly integrated with structured language.
5. It also provides specific structures that can organize the statements.
6. It is used to develop web applications and server pages.

Difference Between PL/SQL and SQL

• SQL can be implemented in several database management systems, while PL/SQL can only be implemented on Oracle databases. It must be standardized, as other similar products do not use it.
• PL/SQL can be described as a non-objected-oriented procedural programming language. Some examples of similar programming languages include C and Pascal. The roots can be traced back to Ada.
• These programming languages are pretty different though both are used to implement SQL queries to create, modify or delete data in the database. The user can implement SQL statements to manipulate objects and data, but it does not include features of programming languages. Some additional features provided by PL/SQL include loops and conditional statements such as IF/THEN. It can be easily implemented with SQL.

Critical Differences Between PL/SQL and SQL

1. SQL is regarded as the data source for generating reports, webpages, and screens. PL/SQL is generally regarded as an application language. The implementation is similar to Java and PHP. It allows users to develop, modify and view reports, web pages, and screens.
2. SQL does not support variables, whereas the user can implement variables, constraints, and data types in PL/SQL.
3. In SQL, the user can implement DDL and DML commands to implement queries on the database, whereas, in PL/SQL, the user can implement code blocks that include functions, triggers, variables, and control and conditionals statements. The control statements include for and while loops, while the conditional statements include if-then-else statements.
4. In SQL, the user can implement a single statement or query. Still, when implementing PL/SQL, the user can implement several operations, or a complete block of statements can be executed simultaneously. It increases the efficiency of the applications by reducing the networking traffic.
5. It is possible to add SQL in a PL/SQL block while the user cannot embed PL/SQL blocks into SQL statements.
6. PL/SQL statements do not directly interact with the databases, whereas SQL statements can perform direct modifications on the database server.
7. It also provides high processing speed when implementing operations to manipulate large volumes of data. It cannot be done by implementing SQL statements alone.

Installing PL/SQL in System

If the user wants to set up PL/SQL in a system, then the user must ensure that Oracle RDBMS is already downloaded and installed.

It is necessary to have Oracle RDBMS as it is responsible for implementing SQL statements. The step-by-step procedure to install PL/SQL in the system is as follows:

1. Download the Setup file for the Oracle database. Launch the installer using the setup file.
2. Enter your email account, click the checkbox, and Select the next button.
3. De-select the checkbox in the next window and select the continue button for the next step.
4. Click on the first option to Create and Configure Database, and click on Next.
5. If you are a beginner and aim to learn PL/SQL from the beginning, then Select the Desktop class option available.
6. Enter a location and change the Oracle base. The other locations will be modified automatically in the software. Click on the next step to move forward.
7. Then click on the Finish button to move to the final step of the configuration. The program will begin installing itself.
8. Once the database files are stored in the location, click the OK button and exit the installation.

Responsibilities of PL/SQL Developer

The responsibilities of a PL/SQL developer include the following activities:

1. The developer is responsible for implementing triggers, advanced PL/SQL communications with the Oracle database, and stored procedures for future use.
2. The developer works with the database administrator to fabricate and manage indexes, tables, and table spaces. They coordinate to perform auditing and quality checks on the data.

They develop the structures for all the physical objects and suggest application modifications by implementing statistical structures. They create and handle tables, indexes, privileges, and database links.