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Parameters and Options

Parameters​

Definition​

Parameters are key elements within Virtual Data Platform. A Parameter is a special kind of variable used for dynamic configuration. Generally, this variable can be used by the user to input values to customize the Virtual Dataset directly in the preferred application like Excel or Power BI. This allows the user's requirements to be passed on to the Source System very easily and quickly.

Additional Information​

Parameters can be created within the Portal by navigating to the section "Virtual Datasets". The steps to create Parameters apply to every Virtual Dataset. To create a new Parameter, select a Virtual Dataset and click on "New Parameter" in the "User parameter" box. A new window pops up where all additional information can be entered. The necessary information may vary depending on the Source System or the Model, as the Source System must offer functionality for dynamic configuration. This implies that, for instance, if one wishes to load a basic CSV file from the web, filtering based on Parameters such as dates or decimals may not be feasible. Conversely, larger Data Warehouse Systems offer numerous types and functionalities that can be utilized by Virtual Data Platform.

Generally, Virtual Data Platform supports the following data types and cardinalities for Parameters. The data type specifies the specific kind of data, while the cardinality defines how the Parameter is treated.

Data Types​

  • String: Represents a sequence of characters, allowing for the storage of text values. Strings are commonly used for storing textual data such as names, addresses, or descriptions.

  • Integer: Denotes whole numbers without any fractional or decimal part. Integers are used to represent counts, quantities, or indices in data sets.

  • Decimal: Encompasses all real numbers, including those with decimal points. Decimals are useful for storing precise numerical values such as monetary amounts or measurements.

  • Boolean: Represents binary values that can only be either true or false. Booleans are frequently used for logical comparisons and conditional statements, where the outcome can only be one of two possibilities.

  • Date & Time: Represents a specific point in time, including both date and time information. In VDP, all dates are assumed to include a time component. If no time is provided, the default time is set to 00:00:00 (midnight). The date and time format follows the pattern YYYY-mm-dd hh:mm:ss.fff.

  • Date: Represents a date without any associated time information. Dates are commonly used to record calendar dates such as birthdays, events, or deadlines. The format typically follows YYYY-mm-dd.

  • Time: Represents a specific time of day without any date information. Times are useful for recording events that occur repeatedly at the same time each day or for scheduling tasks. The format usually follows hh:mm:ss.fff.

Cardinalities​

  • Single Value: Represents a single string, number, or date. It can hold only one value at a time and is commonly used for storing individual pieces of information.

  • Range: Denotes a span between a low and a high value. Ranges are useful for defining intervals or boundaries within a dataset, such as age ranges or price ranges.

  • List: Consists of a collection of single values. Lists allow for storing multiple individual values within a single Parameter, such as a list of names or a list of numeric IDs.

  • Selection: Represents a set of values, including both single values and ranges. Selections offer flexibility in specifying multiple criteria or options for filtering or querying data.

  • Table: Represents a structured set of data organized into rows and columns. Tables allow for storing and manipulating complex datasets with multiple attributes or dimensions, similar to a spreadsheet or database table.

Default value​

If the Parameter is not used when executing the Virtual Dataset it belongs to, the default value will be used. Default values can be single values only and have to be given as strings.

Value Lists​

A Value List can be used to define the set of valid entries for a Parameter. Client tools can make use of these entries to make entering Parameter values more easy.

Parameter Particularities: Empty versus Null​

When controlling Parameters from applications, it's possible that empty values may be inputted or even desired at times. Especially with strings, it's important to understand how Virtual Data Platform handles empty versus null values. An empty value, represented by MyParameter='', indicates that the variable or data field named myparam contains a deliberate absence of data. It signifies that the field is intentionally left blank or does not contain any information. On the other hand, MyParameter= denotes a null value, indicating that the variable or data field named MyParameter explicitly lacks a value or is unknown. In databases and programming, null serves as a specific marker to represent the absence of a value or an undefined state.

The following describes how to use the VDP Syntax to distinguish between empts and null values:

Case 1: MyParameter = '' is entered, '' is also operated in Virtual Data Platform. The corresponding Function syntax looks as follows :

=VDP.GETDATA("MyCategory"; "MyFunction", "MyParameter=''")

Case 2: MyParameter = is not filled, this Parameter is filled with null. In case default values are defined for this Parameter, they are applied. In case not, the MyParatermer's value is forwarded as null to the Source System.

=VDP.GETDATA("MyCategory"; "MyFunction", "MyParameter=")

Case 3: It is required to actively filter for null values (or exclude null, as indicated with the [NOT])

=VDP.GETDATA("MyCategory"; "MyFunction", "MyParameter IS [NOT] NULL")

Case 4: It is required to actively filter for empty values (or exclude null, as indicated with the [NOT])

=VDP.GETDATA("MyCategory"; "MyFunction", "MyParameter IS [NOT] INITIAL")

Options​

Definition​

Options can be used to further specify the Virtual Dataset next to

System​

A Parameter defining the System to be used.

Postprocessing​

Parameters defining postprocessing steps. Parameters used for postprocessing are e.g.:

  • Limit: A number to limit the number of rows returned
  • Order By: A list of columns and order directions to be applied
  • Columns: A list of columns which are selected