使用python在sqlite中同时将数据插入多个表

Question

I am trying to read in multiple files to populate multiple tables in sqlite using python. I am trying to do something like this.

def connect_db():
    return sqlite3.connect(app.config['DATABASE']) # Flask stuff 

# List of tables and corresponding filenames
file_list = ['A','B','C','D']

for file in file_list:
    with closing(connect_db()) as db:
        cursor = db.execute('select * from ' + file)
        # Get column names for the current table
        names = tuple(map(lambda x: x[0], cursor.description))
        filename = file + '.txt'
        with open(filename, 'r') as f:
            data = [row.split('\t') for row in f.readlines()]
            cur.executemany('INSERT INTO' + file + ' ' + str(names) + ' VALUES ' + ???)

Now I realized that in the executemany() statement above, I need to put the syntax (?,?,?) where ? is the number of columns. I can generate a tuple of ? but then they will have quotes around them. ('?', '?', '?'). Is there a way around this? Thanks.

Answer 1

You can implement a query "maker", that loop over a dict or an object properties and build VALUES string with it. I did something like that on some project :

    d = {
        "id":0,
        "name":"Foo",
        "bar":"foobar"
    }

    sql = ""
    for key, foo in d.iteritems():
        # First, copy the current value
        bar = copy.copy( foo )

        # Test if number
        try:
            # try to increase the value of 1
            bar += 1
        except TypeError:
            # if we can't, add double quote 
            foo = '"%s"' % foo

        # concat with the previous sequences
        sql = "%s%s=%s," % ( sql, key, foo )

    # remove the latest comma ...
    sql = sql[:-1]

So the value of "sql" at the end of the loop should be something like this

bar="foobar",id=0,name="Foo"