Posted on February 13, 2023 by Kevin Guisarde .

Dynamic SQL in Telecommunications Industry

Dynamic SQL is a powerful technique used in SQL Server that enables developers to generate and execute SQL statements during runtime. This approach provides greater flexibility and adaptability, as it allows developers to construct SQL statements based on user inputs or other conditions. By utilizing dynamic SQL, developers can build applications that are more responsive to user needs and provide a more personalized experience. In this blog, we will delve into the different types of dynamic SQL and provide examples from the Telecommunications industry, demonstrating how dynamic SQL can be used to create more efficient and effective database applications. Whether you are a seasoned developer or just starting with SQL Server, this blog will help you master dynamic SQL and unleash its full potential.

Agenda

1. Introduction to Dynamic SQL
2. Types of Dynamic SQL
3. Real-World Example Questions in Telecommunications Industry
4. Interview Question and Answer
5. Conclusion

Introduction to Dynamic SQL

Dynamic SQL is a technique used in SQL Server where the SQL statement is generated and executed at runtime. This allows you to write code that is more flexible and adaptable, as you can construct and execute SQL statements based on user inputs or other conditions. In this blog, we’ll explore the different types of dynamic SQL and provide examples from the Telecommunications industry.

Types of Dynamic SQL

Dynamic SELECT Statement

A dynamic SELECT statement is used to generate a SELECT statement at runtime, based on the inputs or conditions. For example, in the Telecommunications industry, you may need to generate a SELECT statement to retrieve data for a specific customer based on their customer ID.

Here’s an example of how you would generate a dynamic SELECT statement in SQL Server:

DECLARE @customerID INT = 123; 
DECLARE @sql NVARCHAR(MAX); 

SET @sql = N'SELECT * FROM Customers WHERE CustomerID = ' + CAST(@customerID AS NVARCHAR(10)); 

EXEC sp_executesql @sql; 

In this example, the @customerID variable is set to 123, and the dynamic SELECT statement is generated using the @sql variable. The sp_executesql system stored procedure is used to execute the dynamic SQL statement.

Dynamic INSERT Statement

A dynamic INSERT statement is used to insert data into a table at runtime. For example, in the Telecommunications industry, you may need to insert data for a new customer into the Customers table.

Here’s an example of how you would generate a dynamic INSERT statement in SQL Server:

DECLARE @firstName NVARCHAR(50) = 'John'; 
DECLARE @lastName NVARCHAR(50) = 'Doe'; 
DECLARE @sql NVARCHAR(MAX); 

SET @sql = N'INSERT INTO Customers (FirstName, LastName) VALUES (''' + @firstName + ''', ''' + @lastName + ''')'; 

EXEC sp_executesql @sql; 

In this example, the @firstName and @lastName variables are set to ‘John’ and ‘Doe’, respectively, and the dynamic INSERT statement is generated using the @sql variable. The sp_executesql system stored procedure is used to execute the dynamic SQL statement.

Dynamic UPDATE Statement

A dynamic UPDATE statement is used to update data in a table at runtime. For example, in the Telecommunications industry, you may need to update the last name of a customer based on their customer ID.

Here’s an example of how you would generate a dynamic UPDATE statement in SQL Server:

DECLARE @customerID INT = 123; 
DECLARE @lastName NVARCHAR(50) = 'Smith'; 
DECLARE @sql NVARCHAR(MAX); 

SET @sql = N'UPDATE Customers SET LastName = ''' + @lastName + ''' WHERE CustomerID = @customerID

Real-World Example Questions in Telecommunications Industry

1. Write a script to generate a table named Customers with columns CustomerID, FirstName, LastName, and PhoneNumber. Populate the table with sample data.

CREATE TABLE Customers ( 
  CustomerID INT PRIMARY KEY, 
  FirstName NVARCHAR(50), 
  LastName NVARCHAR(50), 
  PhoneNumber NVARCHAR(20) 
); 

INSERT INTO Customers (CustomerID, FirstName, LastName, PhoneNumber) 
VALUES 
  (123, 'John', 'Doe', '555-555-1212'), 
  (456, 'Jane', 'Doe', '555-555-1213'), 
  (789, 'Jim', 'Smith', '555-555-1214'); 

2. Write a dynamic SQL statement to retrieve all customers with the last name Doe.

DECLARE @lastName NVARCHAR(50) = 'Doe'; 
DECLARE @sql NVARCHAR(MAX); 

SET @sql = N'SELECT * FROM Customers WHERE LastName = ''' + @lastName + ''''; 

EXEC sp_executesql @sql; 

3. Write a dynamic SQL statement to update the phone number for customer with ID 123 to 555-555-1215.

DECLARE @customerID INT = 123; 
DECLARE @phoneNumber NVARCHAR(20) = '555-555-1215'; 
DECLARE @sql NVARCHAR(MAX); 

SET @sql = N'UPDATE Customers SET PhoneNumber = ''' + @phoneNumber + ''' WHERE CustomerID = ' + CAST(@customerID AS NVARCHAR(10)); 

EXEC sp_executesql @sql; 

Interview Question and Answer

Q: What is Dynamic SQL and how have you used it in a project?

A: Dynamic SQL is a technique used in SQL Server where the SQL statement is generated and executed at runtime. I have used dynamic SQL in a project where I was building a reporting system for a Telecommunications company. The system allowed users to generate reports based on various criteria such as customer information, call data, and billing data. To achieve this, I used dynamic SQL to generate SELECT statements based on the user inputs and then executed those statements to retrieve the data. This approach allowed me to write more flexible and adaptable code that could handle different reporting requirements.

Conclusion

In conclusion, dynamic SQL is a powerful technique in SQL Server that allows you to generate and execute SQL statements at runtime. By using dynamic SQL, you can write code that is more flexible and adaptable, making it easier to handle different scenarios and requirements. In this blog, we explored the different types of dynamic SQL and provided examples from the Telecommunications industry. We also provided real-world example questions and an interview question and answer to help you better understand the concept of dynamic SQL.