✔️ DO provide a value of zero on simple enums.Ĭonsider calling the value something like "None." If such a value is not appropriate for this particular enum, the most common default value for the enum should be assigned the underlying value of zero. They are used to track the state of the enum rather than being one of the values from the set represented by the enum. ❌ DO NOT include sentinel values in enums.Īlthough they are sometimes helpful to framework developers, sentinel values are confusing to users of the framework. Method overloading allows adding parameters in future releases. Such reserved parameters can be expressed as enums with a single default value. ❌ AVOID publicly exposing enums with only one value.Ī common practice for ensuring future extensibility of C APIs is to add reserved parameters to method signatures. Reserved values just pollute the set of real values and tend to lead to user errors. ![]() See Adding Values to Enums for more details on adding values to enums. You can always simply add values to the existing enum at a later stage. ❌ DO NOT provide reserved enum values that are intended for future use. ❌ DO NOT use an enum for open sets (such as the operating system version, names of your friends, etc.). ✔️ DO favor using an enum instead of static constants. ✔️ DO use an enum to strongly type parameters, properties, and return values that represent sets of values. A common example of the flags enum is a list of options. A common example of the simple enum is a set of colors.įlag enums are designed to support bitwise operations on the enum values. Simple enums represent small closed sets of choices. There are two kinds of enums: simple enums and flag enums. To create a SQL table using XML elements, all you have to do is to change the mode value of the OPENXML function to 2 and change the name of the attributes to the name of the element you want to retrieve.Enums are a special kind of value type. In the output you will see values from the Name and Make attributes of the CarInfo element as shown below: In our case the CarInfo element has two attributes Name, and Make, therefore we retrieve both.Īs a final step, we execute the sp_xml_removedocument stored procedure to remove the XML document from the memory. Next, inside the WITH clause, we need to define the name and type of the attributes that you want returned. The mode value of 1 returns the attributes only. The OPENXML function takes three parameters: the handle to the XML document, the path of the node for which we want to retrieve the attributes or elements and the mode. Next, we use the OPENXML function to read the contents of the XML document. ![]() It takes the handle and the document variable as parameters and creates an association between them. The sp_xml_preparedocument performs this task. ![]() To read the attributes and elements of the XML document, we need to attach the handle with the XML document. Next, we create a handle for the XML document. At this point in time, the XML document is loaded into the memory. Next using the SELECT statement we print the contents of the XML file. In the script above we declare an XML type variable The variable stores the result returned by the OPENROWSET function which retrieves XML data in binary format.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |