Working with Common Features of Calculation Views

Every calculation view has a Semantics node. You do not add this, it is already present and will always be the top node (regardless of the type of calculation view). In this node, you assign semantics to each column in order to define its behavior and meaning. This is important information used by consuming clients so that they are able to display and process the columns appropriately.

One of the most important and mandatory settings for each column is its column type. You can choose between attribute or measure. This defines the basic role of the column.

In the semantic node, you can also optionally assign a semantic type to each column. A semantic type describes the specific meaning of each column and this can be helpful to any client that consumes the calculation view by enabling it to then represent the columns in the appropriate format. For example, if you define a column as a date semantic type, the front-end application can format the value with separators rather that a simple string. The key point is that it is the responsibility of the front-end application or consuming client to make use of this additional information provided by the semantic type.

• Assigning a description column to another column - for example, assigning the product id column to a product description column so that a user sees a value which is more meaningful.

• Hiding a column - This can be used if a column is only used in a calculation, or is an internal value that should not be shown, for example, hiding the unhelpful product id when we have assigned a description column that should be shown in its place.

• Assigning a variable - This enables a user to select a filter value at runtime for the attribute.

Apart from the semantic type, there are other important settings that can be defined for each column such as the following:

• One of the most frequently maintained values in the Semantics node is the name and label of the column. It is possible to define an alternative name and label to any column so that it will make more sense to a user than what was originally proposed from the data source.
• For example, who wants to see the word MATNR in a business report column heading when we really should be seeing the words Material Number?

In some cases, you need to use the same data source more than once in a calculation view. Although it is possible to include the same data source multiple times in the same calculation view, each instance needs a unique name to identify it.

In order to support this scenario, you define an alias for any additional instance of the same data source. The alias is found under Properties when you click on the header of the data source.

SAP HANA Cloud has the possibility to sort the result set (output) of any calculation view. This enables you to define a sort order that will apply when none is specified by the client query that is executed on top of the calculation view, thus guaranteeing a stable result order.

It can also be useful when previewing the data for the purpose of testing your calculation views.

Columns, both attributes and measures can contain undefined values or null values. You can handle such cases by defining default values that replaces the null values in reporting tools.

For example, you can replace the column values that would usually appear with the null value representation of '?' with a default value 'Null', or 'Empty' or with any other user defined value that you prefer.

1. Select the Semantics node
2. Choose the Columns tab
3. Select a measure or attribute
4. Select the 'Null Handling' checkbox
5. Optionally, in the Default Value text field, provide a default value

For each calculation view, you can define a number of properties in the View Properties tab of the Semantics node. Depending on the type of calculation view, the list of available properties may vary.

Calculation view properties are organized with four tabs of the semantics node that have the labels General, Advanced, Static Cache, and Snapshots.

The two following tables list the General and Advanced properties of views and give a short description. A number of these properties are described in more detail in the following lessons.