To get SQL once the tree is constructed, you have to flatten it.
— Procedure: sql<-trees [trees...]
Return a string made from flattening trees (a list).
Each element of trees is either a string, symbol, number,
or keyword; or a tree as returned by one of the make-*-tree
procedures. The returned string is marked by sql-pre.
— Procedure: sql-command<-trees [trees...]
Return a string made from flattening trees (a list).
See sql<-trees for a description of trees.
The returned string ends with a semicolon, and is marked
by sql-pre.