The Difference Between SQL and PL/SQL

If you’re familiar with Oracle Databases, you’ll have seen mentions to SQL and PL/SQL, which are both programming languages used to interact with said databases.

In this article, we will cover what these two programming languages are, as well as when you should use which.

SQL 101

When it comes to databases, SQL is the industry-standard programming language developers use to:

  • Create, modify, or delete database objects
  • Query, insert, update, or delete data into database objects

With that said, there is no one set of SQL standards that apply to all relational database management systems. There are a general set of rules to which most (if not all) SQL variants here, but each database management system implements SQL slightly differently. Oracle is not different, and the modification of SQL it uses for its databases differ from that used for Microsoft’s SQL Server, MySQL, PostgreSQL, and so on.

Furthermore, we mentioned that SQL is a programming language. While true, SQL is a minimal language and omits programming constructs that are typically found in others, such as loops and select conditional statements. For this reason, many developers use SQL for their database-related needs and their programming language of choice (e.g., Python, Java) for everything else.

PL/SQL 101

PL/SQL is a uniquely Oracle programming language that complements Oracle’s implementation of SQL. (You will find little use for PL/SQL outside of Oracle’s products!)

PL/SQL, unlike SQL, is similar to a more conventional programming language that includes most (if not all) of the features developer expect, such as conditional statements, loops, and exception handling. However, what makes PL/SQL unique is its built-in ability to integrate seamlessly with SQL.

Using SQL with PL/SQL

Oracle considers PL/SQL to be an extension of SQL, and it allows developers to mix SQL statements with programming/procedural constructs.

Where your SQL statements are declarative (that is, it defines only *what* needs to be done), your PL/SQL code blocks define how things should be done.

Important note: while your PL/SQL code can contain SQL Statements, your SQL statements cannot include PL/SQL code.

Conclusion

To work with Oracle Databases, developers must use Oracle’s variant of SQL. However, SQL is a limited language, and to correct this deficiency, developers can use PL/SQL. PL/SQL is a procedural language that closely mirrors other commonly-used programmings.