How to resolve System.Type to System.Data.DbType?

Question

What is the best way to find System.Data.DbType enumeration value for Base Class Library types in System namespace?

Answer 1

I know it is old question which is already answered, but there is easier way by using SqlParameter, which already has this logic implemented. This is specific for SqlServer, but the providers for Postgre, MySql .. etc have corresponding implementations.

Here is a complete function which handles non-nullable, nullable primitive types, decimal and string

public static DbType GetDbType(Type runtimeType)
{
    var nonNullableType = Nullable.GetUnderlyingType(runtimeType);
    if (nonNullableType != null)
    {
        runtimeType = nonNullableType;
    }

    var templateValue = (Object)null;
    if (runtimeType.IsClass == false)
    {
        templateValue = Activator.CreateInstance(runtimeType);
    }

    var sqlParamter = new SqlParameter(parameterName: String.Empty, value: templateValue);

    return sqlParamter.DbType;
}

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How to get SqlParameter:

For SqlServer, depending on your .netframework version you can find the SqlParamter type in System.Data, System.Data.SqlClient nuget and Microsoft.Data.SqlClient nuget

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Source code for SqlParameter:

The implementation of SqlParameter is using this piece of code which is pretty close to what the accepted answer is proposing.