Change datatype of column SQLite3(Python) - database

Question

I have a database that I am reading with sqlite3 in Python 2.7, using the following command:
# Change to database directory
os.chdir(data)
# Find database file
cur_db = glob.glob('*.db')
# Connect to database
con = sqlite3.connect('database.db')
c = con.cursor()
# Query database
print(len(available_table))
for row in c.execute('SELECT * FROM col1 '):
print row
which gives me something like:
(1, u'2.3', u'brown', u'0', u'hairy', u'banana', u'2', u'monkey')
I would like to look at values in the column w/ the value u'2.3' greater than 2. But this is a unicode string instead of a number, making it difficult to compare to a number (eg 2).
Ideally, I would like something like:
# Connect to database
con = sqlite3.connect('database.db')
c = con.cursor()
# Query database
c.execute('SELECT * FROM critter WHERE weight > 2'.
QUESTION: How can I add a conditional statement to extract only data rows where this element is greater than 2? I would like to leave the database unaltered.

Answer 1

Edit: oh you want a query to do that... You can do:
for row in c.execute('select * from critter where cast(weight as numeric) > 2'):
# do something
Older answer:
If you want to do this on the Python side you can use a try-except construct like so:
for row in c.execute('SELECT * FROM col1'):
try:
val = float(row[1]) # number here is the number of the element in the tuple
if val > 2:
print(val)
except ValueError:
pass