Now let’s dive into inserting data. The INSERT command is one of the fundamental building blocks of the database world, kind of like the hammer or screwdriver we use daily. Isn’t that great? With a few simple commands, you can incorporate massive data into the system. Of course, like in every job, there are some points to watch out for. Otherwise, things can get out of control, believe me. If you insert incorrect data once, fixing it later is a different headache, finding it is a different ordeal. It’s like searching for a needle in a haystack 🙂
The INSERT command is actually based on a pretty simple logic. Suppose you have a table and want to add new records into it. That’s where INSERT comes into play. You say, “Hey, database, add these details to this table,” and it happily does that. By the way, the database we’re talking about isn’t some kind of wizard; it’s a structure that works according to specific rules. So, even if it looks complex, it has a very clear logic underneath.
The most basic usage of INSERT is to assign values to all columns. That is, when entering a new record into a table, you provide a value for each of the table’s columns. This is actually one of the most reliable methods because it clearly states which data goes where. It’s like buying a new house and choosing the furniture for all rooms. Sofa for the living room, bed for the bedroom, refrigerator for the kitchen… Everything is in its place.
What if we want to insert data into only some columns? Here, things change a bit. You don’t have to provide values for all columns, but you need to specify which columns you are inserting data into. Just like filling out a form, some fields are mandatory, and others are optional. The optional fields can be left blank if they are allowed to accept NULL values, otherwise you’ll get an error. This is an important detail.
For example, consider a scenario: you have a customer table with columns for customer name, surname, email, phone, and address. Suppose you are registering a new customer but don’t have the phone number yet. In this case, you can create the record by leaving the phone column NULL. This provides flexibility without compromising data integrity. Isn’t that nice?
Another great feature of the INSERT command is that instead of directly assigning values to certain columns, you can insert the results of a query. That is, you can transfer data from another table with a single command. This can be a lifesaver in data transfer or synchronization operations. It’s like carrying a bunch of stuff from one place to another in one go, as if teleporting. Super cool.
Let’s look at the code part. Coding in database operations makes things much more dynamic. You might want to add data from a user in a web application directly to the database. Here’s where C# and similar languages come in. For example, in an ASP.NET Core project, we will see how to add data received from the user into PostgreSQL using Dapper. By the way, Dapper is a very useful ORM (Object-Relational Mapper) that allows you to write SQL queries directly within your C# code, which speeds things up and improves readability. This is basically the essence of it, right? Making tasks easier, faster, clearer.
Below is a simple C# code example. In this example, we have a class called ‘Product’ and we add the information of this class into the ‘Products’ table in PostgreSQL. Let’s start with a ‘Wrong’ example, i.e., code vulnerable to SQL injection, to understand why we shouldn’t do it. Then, we’ll show the safe way using Dapper. You know the saying, ‘See the mistake first, then understand the correct way.’ That’s exactly what we’ll do.
// WRONG METHOD: Vulnerable to SQL Injection! public async Task AddProductWrong(Product product) { var connectionString = _configuration.GetConnectionString("hl=us"); using (var connection = new NpgsqlConnection(connectionString)) { connection.Open(); // Warning: This query is vulnerable to SQL Injection attacks! Do not use! string query = $"INSERT INTO Products (Name, Price, Stock) VALUES ('{product.Name}', {product.Price}, {product.Stock})"; await connection.ExecuteAsync(query); } return Ok("Product added with wrong method."); } Did you see? Those quotes and string concatenation make your code dangerously vulnerable. If someone sends ‘product.Name’ as `’ OR ‘1’=’1′ –`, your database could be compromised. Never do this. Code like this can fail the class exam 🙂
Now, let’s move to the right and secure method. We’ll use Dapper’s parameterized query feature. This way, the values we send won’t be directly embedded in the SQL query; instead, they’ll be safely processed. It’s like receiving a letter and checking it before opening, to see if there’s anything harmful inside. We’ll use Npgsql library for PostgreSQL.
// CORRECT METHOD: Secure INSERT with Dapper public async Task AddProductSecure(Product product) { var connectionString = _configuration.GetConnectionString("hl=us"); using (var connection = new NpgsqlConnection(connectionString)) { connection.Open(); string query = @"INSERT INTO Products (Name, Price, Stock) VALUES (@Name, @Price, @Stock)"; // Parameters are indicated with @ await connection.ExecuteAsync(query, new { product.Name, product.Price, product.Stock }); // Parameters are assigned with an anonymous object } return Ok("Product added securely using Dapper."); } That’s it! As you saw, using parameters like @Name, @Price, @Stock, and passing values via an anonymous object makes the query much safer. This method should be used in updating, fetching, and inserting data. As always, web security courses emphasize, “Never execute user input directly.” This is a practical implementation of that principle.
In summary, the INSERT command is essential in database management. From basic usage to inserting query results, there are many ways. Coding practices should prioritize security. Tools like Dapper help us a lot with that. Remember, good coding isn’t just about working; it’s about being secure and sustainable. By the way, coding outdoors in Bursa can be wonderful. That’s all for now, I hope it was helpful 🙂