DB Query Reader

Executes an entered SQL query and returns the result as KNIME data table.



SQL Statement
SQL editor to enter the SQL statement that returns the result data. This node supports complex queries, but may not be used for anything but queries. It can be also used to execute none "SELECT" statements that return any data such as a "DESCRIBE" statement etc.
To open code completion press <CTRL> + <SPACE>. Table and columns names are only suggested if the metadata is available e.g. shown in the Database Metadata Browser. To perform undo press <CTRL> + Z and for re-do <CTRL> + Y.
If the node consumes a lot of memory you might want to decrease the "Fetch size" in the "Advanced" tab of the corresponding connector node. The fetch size specifies how many rows are fetched from the database server into KNIME per network round trip. The higher the number the more memory is consumed. However the smaller the number the more network round trips are necessary to fetch large results. Also not all JDBC driver support this option and thus might ignore it.
Database Metadata Browser
The Database Metadata Browser allows you to browse the database metadata and to select a table or view. Click the Refresh button at the bottom right to re-fetch the metadata from the database. The data is grouped by database schema and type e.g. view or table. By clicking on an entity it shows contained elements. If you click on a table or view the dialog will fetch the column names and types of the selected element. To select a table or view select the name and click OK or double click the element. To search for a particular table or view enter the name or parts of the name into the search field and click on the Magnifying Glass button or press enter.
Flow Variable List
The list contains the flow variables that are currently available at the node input. Double clicking any of the entries will insert the respective identifier at the current cursor position (replacing the selection, if any).

Input Type Mapping

This tab allows you to define rules to map from database types to KNIME types.

Mapping by Name
Columns that match the given name (or regular expression) and database type will be mapped to the specified KNIME type.
Mapping by Type
Columns that match the given database type will be mapped to the specified KNIME type.

Input Ports

DB Connection to the database.

Output Ports

KNIME data table with the result from the database query.


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