I have a list of street names in this format:

STRNAME
Elsinore
Neil Young
Penny
Fall

And a shapefile ("input_streets") with street names in this format:

STREET
Elsinore Av
Neil Young St
Penny Lane
Fall Dr

I want to select streets in the "input_streets" shapefile that are also found in the 1st list, but you can see my challenge, the first list doesn't have the street suffixes, the second list does. This means a simple expression like this won't work:

expression = '"STREET" = '+ "'"+ strname"'" 

...where "strname" is just the "STRNAME" values from the first list. The suffixes in "STREET" values 'get in the way'.

I need a way to give QGIS an expression that can compare ONLY the Street Names (their Prefixes, Ignoring the Suffixes, whatever they happen to be: St, Lane, Rd, etc.)

Something like:

street = STREET[0:firstspace]

But can this be done? Can one refer to the column heading of a table with RESTRICTIONS on HOW MUCH of the column value to USE in an expression? (ie. "give me the value in STREET but stop at the first space")

Example:

street = STREET[0:firstspace]
expression = 'street = '+ "'"+ strname"'" 

Or can one only refer to the column heading in an expression, and whatever values happen to be in that column, you're stuck with?