With nothing selected, the toolbar lists the available building blocks in descending order of frequency. Select an item and click the canvas to place it.
| Toolbar | Places |
|---|---|
| Relation | A base relation, a leaf node of the query tree |
| Selection, Projection | The unary operators σ and π |
| Join menu | Natural join, theta join, semi join, anti semi join |
| Others menu | Difference, division, union, intersection |
| Result | The root of the query tree |
Connect the nodes
- Select an operator or the result.
- Click Connect (Shift + C). A message in the bottom bar names the operator being connected.
- Click the relation or operator that feeds it. The two are linked by a branch.
An element cannot be connected to itself; any other connection is accepted as drawn.
Edit and remove
- To rename a relation, select it and click Rename, or double-click it. Each relation is assigned a default name, such as
RELATION1. Names can contain letters, digits and underscores, but cannot begin with a digit. All names are automatically converted to uppercase. - Delete removes the selected element together with its branches.
- The zoom buttons adjust the view for large trees.