KNIME Documentation

Read data from a database ​

Read a database table or custom query result into a KNIME data table using the DB Table Selector and DB Reader nodes.

Before you begin ​

Select and read a table ​

Configure a DB Table Selector node to choose a table or query, then read the result with a DB Reader node.

  1. Connect the output port of the connector node to a DB Table Selector node.
  2. Click DB Table Selector once to open its configuration.
  3. Enter the Schema and Table/View name, or click Select a table to open the Database Metadata Browser and pick from a list of available tables and views.
  4. To write a custom SQL query instead, tick Custom Query and enter a SELECT statement. Use the placeholder #table# to reference the table selected via the browser.
  5. Optionally, configure Input Type Mapping rules to override how database types map to KNIME types. See Type mapping.
  6. Click Apply.
  7. Connect a DB Reader node to the DB Table Selector output port.
  8. Execute the DB Reader node. It runs the SQL query in the database and outputs the result as a KNIME data table.

Use the Database Metadata Browser ​

The Database Metadata Browser displays the database schema, including all tables, views, and their columns with data types.

  • Click a schema, table, or view to expand it.
  • Select a table or view and click OK, or double-click it to confirm the selection.
  • Use the search box at the top to find a table or view by name.
  • Click the Refresh button (lower right) to reload the schema if changes have occurred since you opened the browser.

Next steps ​