AddWithValue

AddWithValue is a method commonly found in database access libraries, particularly those interacting with SQL databases. Its primary purpose is to add a parameter to a command object along with its corresponding value. This is a crucial step in preventing SQL injection vulnerabilities, a common security threat where malicious SQL code is inserted into database queries.

When constructing SQL queries dynamically, it is important to separate the SQL command structure from the data values. Using parameterized queries, like those facilitated by AddWithValue, ensures that the provided values are treated strictly as data, not as executable SQL code. This separation prevents any injected code from being interpreted by the database engine.

The AddWithValue method typically takes two arguments: the name of the parameter and its value. The parameter name is usually prefixed with a symbol like '@' or ':' depending on the specific database provider. The value can be of various data types, and the method often infers the appropriate database type from the .NET type of the provided value. While convenient, some developers prefer to explicitly specify the data type using an overload of the Add method to ensure greater control and potentially better performance. However, for many common scenarios, AddWithValue offers a straightforward and secure way to parameterize database commands.