Dynamic SQL and Embedded SQL

Structured Query Language (SQL) is the standard language used to interact with relational databases. SQL statements can be categorized into two main types: dynamic SQL and embedded SQL. In this blog, we will explore the differences between dynamic SQL and embedded SQL and their respective use cases. We will also see side by side comparison of both the methods.

Dynamic SQL and Embedded SQL are two methods that developers can use to interact with relational databases in programming languages. While both approaches have the same goal of executing SQL statements and retrieving data from a database, they differ in the way SQL statements are constructed and executed.Dynamic SQL is a technique used in database programming that allows SQL statements to be constructed and executed at runtime. This approach offers more flexibility than Embedded SQL because the SQL statement is constructed based on dynamic criteria that can change at runtime. For example, if a user wants to search for products based on different criteria, Dynamic SQL would be a suitable approach because the SQL statement can be constructed based on the user’s inputs.

However, as every coin has two sides Dynamic SQL also comes with some drawbacks. Since the SQL statement is constructed dynamically, it can pose a security risk if not implemented properly. If an attacker is able to manipulate the input criteria, they can potentially inject malicious SQL code and access or modify sensitive data in the database. Developers need to take precautions such as validating inputs and using parameterized SQL statements to prevent SQL injection attacks.

Let us see some use cases of dynamic SQL :-

1. An online shopping website needs to retrieve products based on user search queries. By using Dynamic SQL, the website can construct the SQL query based on the user’s input. For example, if the user is searching for products from a specific brand, the website can construct the SQL query to retrieve all products from that brand. If the user is searching for products within a specific price range, the website can construct the SQL query to retrieve products that fall within that range.
   Dynamic SQL allows the website to handle complex search queries that are difficult to express in a static SQL query. The search criteria can be changed dynamically, allowing users to easily find products that meet their needs.
2. A healthcare application allows doctors to search for patient records based on various criteria such as name, age, gender, medical history, etc. By using Dynamic SQL, the application can construct the SQL query based on the inputs provided by the doctor. For example, if the doctor is searching for patients with a specific medical condition, the application can construct the SQL query to retrieve all patient records that match that condition.
   Dynamic SQL allows the application to handle complex search queries that are difficult to express in a static SQL query. The search criteria can be changed dynamically, allowing doctors to quickly find patient records that meet their requirements.

Embedded SQL, on the other hand, is a technique where SQL statements are precompiled into a program before execution. The SQL statements are fixed at compile time, so the execution time is much faster than Dynamic SQL. This approach is ideal when the query criteria are known in advance, such as when generating daily reports, or performing batch processing of large amounts of data.

One benefit of Embedded SQL is that it is less prone to security risks than Dynamic SQL because the SQL statements are pre-compiled and validated at compile time. Additionally, Embedded SQL provides better performance than Dynamic SQL, since there is no overhead involved in constructing SQL statements at runtime.Despite its benefits, Embedded SQL also has some drawbacks. It lacks the flexibility of Dynamic SQL, which means that if query criteria change, one needs to modify and recompile the program. This can be a time-consuming and expensive process, particularly in large-scale applications with many users.

Let us see some use cases of Embedded SQL :-

1. A banking application needs to generate daily reports of all transactions made by customers. By using Embedded SQL, the application can pre-compile and optimize the SQL query for fast execution. The query criteria are fixed, and the performance of the query is critical.
   The application can generate daily reports automatically, ensuring that the bank has an accurate record of all transactions. Since the SQL query is optimized, the application can generate reports quickly and efficiently, even when dealing with large datasets.
2. An accounting software needs to generate financial statements for a company. By using Embedded SQL, the software can pre-compile and optimize the SQL query for fast execution. The query criteria are fixed, and the performance of the query is critical.The software can generate accurate financial statements quickly and efficiently, even when dealing with large datasets. Since the SQL query is optimized, the software can generate reports quickly and efficiently, ensuring that the company has an accurate record of its finances.

The following table will help you understand the differences more clearly :-

Fig1: Difference between Dynamic and Embedded SQL

But the main question is how to decide which method to use ?The answer is very simple, for that one should consider their specific use case. Dynamic SQL is suitable when query criteria are unknown or dynamic, while Embedded SQL is appropriate when query criteria are fixed and performance is critical.One should also consider security risks and take necessary measures to ensure that SQL statements are properly validated and parameterized to prevent SQL injection attacks.

Hopefully this blog has helped you gain some knowledge. Keep learning.

Authors :-

1. Bhushan Sangle
2. Arnav Shah
3. Avadhut Sawant
4. Sameer Vyawahare
5. Mahesh Sathe