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C# – How to handle nulls with SqlDataReader

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SqlDataReader returns a DBNull object when a column is null. This isn’t the same as a C# null. You can check if the column is null by comparing it with DBNull.Value or by using SqlDataReader.IsDBNull(). Here’s an example showing these two ways of checking if a column is null: After checking if the column is … Read more

Error: Cannot convert null to type parameter ‘T’

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Problem You’re trying to return null from a generic method and you’re getting the following compiler error: Cannot convert null to type parameter ‘T’ because it could be a non-nullable value type. Consider using ‘default(T)’ instead You can’t return null because the compiler doesn’t know if T is nullable. Solution There are a few options … Read more

C# – Use Convert.ChangeType to convert string to any type

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You can use Convert.ChangeType() to convert from a string to any type, like this: Normally you’d call the specific type converter method, such as when you’re converting a string to an int. However, sometimes it makes sense to use the generalized type converter method – Convert.ChangeType() – instead of hardcoding the calls to specific type … Read more