SQL vs PL/SQL: Difference Between SQL & PL/SQL

Even though PL/SQL and SQL are tightly interwoven, there are some variations in how they operate. PL/SQL can execute a complete block of code, whereas SQL can only execute one query at a time. SQL and PL/SQL differ from one another in terms of performance, error handling, and database interaction. In this article, we'll go over all of the differences between the two languages so you can understand how they're used.

SQL: Brief Overview

The Structured Query Language (SQL) is a strong non-procedural database language for managing relational databases. When compared to procedural languages, it is very portable, upgradeable, and offers a high degree of abstraction. It was developed by IBM research. End-users can interface with a variety of database management systems using SQL, depending on their availability.

PL/SQL: Brief Overview

PL/SQL is a strong procedural language that allows you to write SQL statements using procedural constructs. It's noted for its fast-processing speed and ability to handle errors.

In PL/SQL, functions, triggers, packages, and other enhancements to an operation's capability are run in blocks of code or numerous statements at the same time. This also aids in network traffic reduction.

The program blocks in the block-structured language can be of two types:

When a block of code isn't saved in your database, it's called an anonymous block.

When a block is named and stored as a parsed representation in your database, it is referred to as a stored procedure.

Key Differences Between SQL and PL/SQL

SQL stands for Structural Query Language, and it was designed to work with relational databases. It's a detail-oriented, declarative language. PL/SQL, on the other hand, is a Procedural/Structured Query Language that uses SQL as its database. It's a programming language that focuses on applications.

SQL has no variables, but PL/SQL provides variables, constraints, data types, and other features.

To write queries and commands in SQL, we use DDL and DML, but in PL/SQL, we utilize code blocks comprising functions, triggers, variables, control structures (for loop, while), and conditional expressions (if...then...else).

A single operation or query can be run at a time in SQL. Multiple operations or a complete block of close can be done at once in PL/SQL. As a result, network traffic is minimized.

It is feasible to embed in a PL/SQL block, but not the other way around.

Unlike PL/SQL, SQL has direct communication with the database server.

PL/SQL has a fast-processing speed and can manipulate large amounts of data quickly. This isn't possible with SQL.

SQL vs PLSQL: Execution

Execution in SQL

In SQL, we have statements, which are simple instructions that tell SQL what they want to happen. SQL then compiles these instructions and performs the work by navigating the database.

SQL statements must be used to carry out all operations. In addition, there are some words in SQL that are designated for specific tasks. SELECT, UPDATE, and DELETE, for example. These names cannot be used for any other reason. (Note: SQL does almost all operations, however, there are tools and apps available to make SQL's job easier.)

In SQL, there are six different sorts of statements.

• Data Manipulation Language statements (DML)

• Data Definition Language statements (DDL)

• Transaction Control statements

• Session Control statements

• System Control statements

• Embedded SQL statements

In SQL queries, the most widely used statements are Data Manipulation Language statements and Data Definition Language statements. So, here's a quick comparison of the two:

Data Manipulation Statements (DML)

SELECT, DELETE, INSERT, and UPDATE are examples of DML statements. They are mostly used to alter data stored in a database. DML statements can be used to delete or add rows, select a specific table or several tables, select a view, edit values in existing rows, and so on.

Here's an illustration:

SELECT ename, mgr, comm + sal FROM emp;

INSERT INTO emp VALUES

(4321, ‘ROBERT’, ‘ACCOUNTANT’, 9876, ’14-JAN-1982′, 1600, 500, 30);

DELETE FROM emp WHERE ename IN (‘WARD’,’JONES’);

Data Definition Statements (DDL)

You can build a schema object, change its structure, rename it, or drop it using DDL statements. You don't have to destroy the entire structure to erase all the data in a schema object. DDL statements can also be used to conduct a variety of additional tasks.

CREATE, ALTER, DROP, TRUNCATE, ANALYSE, and COMMENT are a few examples of DDL statements.

Here's an illustration:

CREATE TABLE plants

(COMMON_NAME VARCHAR2 (15), LATIN_NAME VARCHAR2 (40));

DROP TABLE plants;

GRANT SELECT ON emp TO Scott;

REVOKE DELETE ON emp FROM Scott;

Execution in PL/SQL

Procedures are stored in the database and called by an application when needed. They can also be accessed through a PL/SQL block (anonymous or stored). When an application calls a procedure, it is compiled and loaded into the System Global Area, where it is processed by PL/SQL and SQL utilizing their respective executors.

Every PL/SQL software unit is represented by a block, which is made up of declarations and statements. It can be nested to contain more blocks.

The following keywords are used to identify them.

• DECLARE – This command is used to declare variables, subprograms, and local types. To prevent clutter, a declarative section of a block terminates when execution is completed.

• BEGIN – includes statements that have declaration access. This is the block's executable portion.

• EXCEPTION - this is where any exceptions raised during execution are handled. To eliminate exceptions in the same, the exception handling component of the block is frequently placed after a subprogram.

• END

Another key feature of PL/SQL is its control structures, which aid in the regulation of statement flow. When creating Triggers, these are vital.

They can be divided into three categories.

Control on a conditional basis: This includes IF-THEN-ELSE statements, in which if tests for a condition, ELSE specifies the action to take, and ELSE specifies what to do if the condition is false.

Loop statements are examples of iterative control since they allow you to repeat an action numerous times. Here you'll find FOR, WHILE, and WHEN.

Sequential Control: This allows you to jump from one label to the next without having to apply any criteria. (This is a GOTO statement)

Usage of SQL and PL/SQL

SQL statements are a fantastic alternative for developing analytical reports because of their detail-oriented nature and the fact that they can directly interface with databases. It can also be used in supporting apps that require simple updating because it writes DML statements. It is primarily intended for data processing and does so.

PL/SQL is a programming language that is mostly used to create applications, such as user interfaces and back-end logic for web pages. For these PL/SQL-based programs, SQL is in charge of providing data. To construct complicated logic, PL/SQL can be combined with Java and PHP.

Conclusion

As we all know, PL/SQL is a SQL extension that performs the same operations, control structures, and triggers as SQL, but on a much larger scale. SQL simply tells you what to do, whereas PL/SQL also teaches you how to do it.