There are two ways to add a sub-query.
In the Columns Pane, right click on the Expression
or Criteria column. From the drop-down menu, select Insert
SubQuery.
Type "(Select)" in the Expression column
and type either "= (Select)", "In (Select)",
or any other valid sub-query expression, in the Criteria column.
CONNX creates a new sub-query tab. Switch to the sub query tab to visually edit the sub-query the same way you edit the main query.
There are two ways to switch to the sub-query tab:
Click the sub-query tab.
In the sub-query cell, click the ellipsis button. If the cell contains more than one sub-query, a drop-down menu appears. Select the sub-query you want.