DB GroupBy

This node allows rows to be grouped by the selected columns from the input DB Data object. Within the dialog, an SQL GROUP BY clause is interactively created by selecting the columns to group by and the columns to aggregate.

The columns to aggregate can be either defined by selecting the columns directly, by name based on a search pattern or based on the data type. Input columns are handled in this order and only considered once e.g. columns that are added directly on the "Manual Aggregation" tab are ignored even if their name matches a search pattern on the "Pattern Based Aggregation" tab or their type matches a defined type on the "Type Based Aggregation" tab. The same holds for columns that are added based on a search pattern. They are ignored even if they match a criterion that has been defined in the "Type Based Aggregation" tab.

The "Manual Aggregation" tab allows you to change the aggregation method of more than one column. In order to do so select the columns to change, open the context menu with a right mouse click and select the aggregation method to use.

In the "Pattern Based Aggregation" tab you can assign aggregation methods to columns based on a search pattern. The pattern can be either a string with wildcards or a regular expression. Columns where the name matches the pattern but where the data type is not compatible with the selected aggregation method are ignored. Only columns that have not been selected as group column or that have not been selected as aggregation column on the "Manual Aggregation" tab are considered.

The "Type Based Aggregation" tab allows to select an aggregation method for all columns of a certain data type e.g. to compute the mean for all decimal columns (DoubleCell). Only columns that have not been handled by the other tabs e.g. group, column based and pattern based are considered. The data type list to choose from contains basic types e.g String, Double, etc. and all data types the current input table contains.

A detailed description of the available aggregation methods can be found on the 'Description' tab in the node dialog.

Options

Groups

Group settings: Select one or more column(s) according to which the group(s) is/are created.

Advanced settings

Column naming

The name of the resulting aggregation column(s) depends on the selected naming schema.

Keep original name(s): Keeps the original column names.
Aggregation method (column name): Uses the aggregation method first and appends the column name in brackets
Column name (aggregation method): Uses the column name first and appends the aggregation method in brackets

Add COUNT(*)

Tick this option to add a column that contains the result for the COUNT(*) operation e.g. the number of rows per group.

column name

The name of the COUNT(*) column. Only enabled if the "Add COUNT(*)" option is selected.

Manual Aggregation

Aggregation settings: Select one or more column(s) for aggregation from the available columns list. Change the aggregation method in the Aggregation column of the table. You can add the same column multiple times. In order to change the aggregation method of more than one column select all columns to change, open the context menu with a right mouse click and select the aggregation method to use.
Parameter: The parameter column shows an "Edit" button for all aggregation operators that require additional information. Clicking on the "Edit" button opens the parameter dialog which allows changing the operator specific settings.

Pattern Based Aggregation

Aggregation settings: Use the "Add" button to add a new row with a search pattern to the aggregation settings. The search pattern can either be a string with wildcards or a regular expression. Supported wildcards are * (matches any number of characters) and ? (matches one character) e.g. KNI* would match all strings that start with KNI such as KNIME whereas KNI? would match only strings that start with KNI followed by a fourth character. Double click the "Search pattern" cell to edit the pattern. The cell is colored in red if the pattern is invalid.
RegEx: Tick this option if the search pattern is a regular expression otherwise it is treated as string with wildcards ('*' and '?').
Parameter: The parameter column shows an "Edit" button for all aggregation operators that require additional information. Clicking on the "Edit" button opens the parameter dialog which allows changing the operator specific settings.

Type Based Aggregation

Aggregation Settings

Select one or more data type from the available type list. Change the aggregation method in the Aggregation column of the table. You can add the same data type multiple times. The list contains standard types e.g. Double, String etc. and all types of the input table.

Parameter

The parameter column shows an "Edit" button for all aggregation operators that require additional information. Clicking on the "Edit" button opens the parameter dialog which allows changing the operator specific settings.

Type matching

Strict: the type based aggregation method is only applied to columns of the selected type.
Include sub-types: the type based aggregation method is also applied to columns containing sub-types of the selected type. For example Boolean is a sub-type of Integer, Integer of Long, and Long of Double.

Input Ports

: DB Data to apply group by.

Output Ports

: DB Data with grouped rows.

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Installation

To use this node in KNIME, install the extension KNIME Database from the below update site following our NodePit Product and Node Installation Guide:

v5.3

A zipped version of the software site can be downloaded here.

Plugin provider: KNIME AG, Zurich, Switzerland

Plugin version: 5.3.2.v202409010954

On NodePit since: 2024-07-09

Last update: 2024-11-20

KNIME versions: Since v3.6

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