Parameters.Add vs. Parameters.AddWithValue: What's the Real Difference and Which Should I Use?

Detailed explanation of the differences between Parameters.Add and Parameters.AddWithValue

The

Parameters.Add method allows you to specify parameter name, SqlDbType and value. The correct syntax is as follows:

command.Parameters.Add("@ID", SqlDbType.Int);
command.Parameters["@ID"].Value = customerID;

In contrast, Parameters.AddWithValue has a more concise syntax and does not require specifying SqlDbType:

command.Parameters.AddWithValue("@demographics", demoXml);

However, when using Parameters.AddWithValue with the same syntax as Parameters.Add, no compilation error occurs. Interestingly, the code also executes normally.

In-depth explanation

Internally, both methods use the same method:

return this.Add(new SqlParameter(parameterName, value));

Parameters.AddWithValue was introduced to replace Parameters.Add to improve code clarity. In the overload of Parameters.Add, the second argument is of type object, which can lead to confusion about which overload to use. This distinction is important because overloading has very different behavior.

Consider the following example:

SqlCommand command = new SqlCommand();
command.Parameters.Add("@name", 0);

Although it looks like it calls the Add(string name, object value) overload, it actually calls the Add(string name, SqlDbType type) overload. This is because 0 is implicitly convertible to an enumeration type.

Therefore, using Parameters.AddWithValue removes potential ambiguities and improves code readability. It is recommended to use Parameters.AddWithValue in preference to get clearer and easier to maintain code.

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