Create a couple of SQL (postgreSQL) statments to identify creeks in crossing in a DB

Hi I am building a map using two separate creek data sets (OSM creeks and DEM derived creeks). The OSM data is generally more reliable, but there are only a small number of creeks. I am wanting to find all the creeks in the DEM dataset that are NOT already in the OSM dataset. (so they can be shown on a map). I am happy to ignore a DEM creek if it is crosses an OSM creek twice or more times (if it crosses just once then it is more likely a side creek) Your job is to develop a SQL statement that will 1) Display all DEM_creeks that do not cross any single OSM creek more than once. 2) Delete all DEM_creeks that cross a single OSM creek more than once I will provide full details of the tables and ca provide SSH access to the server so you can play with the SQL. Matt :) ## Deliverables The image attached gives a sense for the overlapping creek issue.