How to Securely Execute Parameterized Queries in MySQL using C#?

Parameterized Query in MySQL with C#

Parameterized queries are an important part of database programming. They allow you to separate the SQL statement from the data that is used in the query. This helps to prevent SQL injection attacks and can make your code more readable and maintainable.

To use a parameterized query in C#, you need to create a MySqlCommand object and add parameters to it. You can do this using the Parameters property of the MySqlCommand object.

The following code shows an example of how to use a parameterized query to select data from the USERS table:

private String readCommand = "SELECT LEVEL FROM USERS WHERE VAL_1 = ? AND VAL_2 = ?;";

public bool read(string id)
{
    level = -1;
    MySqlCommand m = new MySqlCommand(readCommand);
    m.Parameters.Add(new MySqlParameter("", val1));
    m.Parameters.Add(new MySqlParameter("", val2));
    MySqlDataReader r = m.ExecuteReader();
    if (r.HasRows)
        level = Convert.ToInt32(r.GetValue(0).ToString());
    r.Close();
    return true;
}

This code will compile and run without errors. However, it will not return the expected results. The problem is that the parameter names in the SQL statement do not match the parameter names in the MySqlCommand object.

To fix this problem, you need to change the parameter names in the SQL statement to match the parameter names in the MySqlCommand object. You can do this by using the @ character followed by the parameter name.

The following code shows how to fix the problem:

private String readCommand = "SELECT LEVEL FROM USERS WHERE VAL_1 = @param_val_1 AND VAL_2 = @param_val_2;";

public bool read(string id)
{
    level = -1;
    MySqlCommand m = new MySqlCommand(readCommand);
    m.Parameters.AddWithValue("@param_val_1", val1);
    m.Parameters.AddWithValue("@param_val_2", val2);
    level = Convert.ToInt32(m.ExecuteScalar());
    return true;
}

This code will compile and run without errors. It will also return the expected results.

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