SQL Use Cases with Example Source Code

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SQL (Structured Query Language) is a programming language used to manage and manipulate relational databases. Here are some common use cases for SQL, along with examples of source code to help you get started:

Data retrieval: SQL can be used to retrieve data from a database using the SELECT statement. Here’s an example of SQL code that retrieves all records from a table called “employees”:
```
SELECT * FROM employees;
```
Data filtering: SQL can be used to filter data based on specific criteria using the WHERE clause. Here’s an example of SQL code that retrieves all records from the “employees” table where the “department” column is equal to “sales”:
```
SELECT * FROM employees WHERE department = 'sales';
```
Data sorting: SQL can be used to sort data based on specific columns using the ORDER BY clause. Here’s an example of SQL code that retrieves all records from the “employees” table and sorts them in ascending order based on the “last_name” column:
```
SELECT * FROM employees ORDER BY last_name ASC;
```
Data aggregation: SQL can be used to perform calculations and aggregate data using functions like COUNT, SUM, AVG, and MAX. Here’s an example of SQL code that calculates the average salary for employees in the “sales” department:
```
SELECT AVG(salary) FROM employees WHERE department = 'sales';
```

Data modification: SQL can be used to insert, update, and delete data in a database using the INSERT, UPDATE, and DELETE statements. Here’s an example of SQL code that inserts a new record into the “employees” table:

INSERT INTO employees (first_name, last_name, department, salary) 
VALUES ('John', 'Doe', 'marketing', 50000);

Data joining: SQL can be used to join data from multiple tables using the JOIN statement. Here’s an example of SQL code that retrieves all records from the “employees” and “departments” tables and joins them on the “department_id” column:

SELECT employees.*, departments.name 
FROM employees 
JOIN departments ON employees.department_id = departments.id;

These are just a few examples of the many use cases for SQL. With its simple syntax and powerful features, SQL is a versatile language that can be used to manage and manipulate data in a wide range of applications.