What are the advantages and disadvantages of using relational SQL databases?

Advantages of relational SQL databases:

• Structured data: data is stored in tables with clearly defined schemas, making it easier to organize and understand.
• Transaction support: provide atomicity, consistency, isolation, and durability (ACID), which is important for data-critical applications.
• Powerful query language (SQL): allows flexible and efficient execution of complex queries, table joins, and aggregations.
• Wide support and maturity: many tools, libraries, and communities.

Disadvantages:

• Scalability: horizontal scaling (sharding) is more complex than some NoSQL solutions.
• Rigid schema: changing table structures can be labor-intensive and require migrations.
• Performance: may lag behind NoSQL when dealing with very large data volumes or specific load types (e.g., document storage).

Example of usage in C# with Entity Framework:

using(var context = new AppDbContext())
{
    var users = context.Users.Where(u => u.IsActive).ToList();
}