Python Generate Create Table

Question

I have a table in which all the 120 fields have got type varchar(75). I have coded like this.

sql = "create table " + tableName + "("
for i in range(len(flds)):
    if i == len(flds) - 1:
        sql += flds[i] + " varchar(75))"
    else:
        sql += flds[i] + " varchar(75), "

Is it possible to get a one-liner for it?

Thanks!

Answer 1

First, let's use join so we don't need the commas and if. And, while we're at it, we can just loop over flds instead of range(len(flds)):

columns = []
for fld in flds:
    columns.append(fld + " varchar(75)"

Of course this means we have to add the ) on at the end:

sql += ', '.join(columns) + ')'

Now we can turn that loop into a comprehension:

columns = (fld + " varchar(75)" for fld in flds)

And now, we can inline that into the join:

sql += ', '.join(fld + " varchar(75)" for fld in flds) + ')'

And now, we have two lines that can obviously be combined into one:

sql = "create table " + tableName + "(" + ', '.join(fld + " varchar(75)" for fld in flds) + ')'

But that's way over 80 characters, so probably better to write it as two lines anyway. I'd probably do it like this:

columns = ', '.join(fld + " varchar(75)" for fld in flds)
sql = "create table " + tableName + "(" + columns + ")"

And finally, let's use an f-string instead of concatenating with +, which makes things only a little shorter, but a lot more readable.

columns = ', '.join(f'{fld} varchar(75)' for fld in flds)
sql = f'create table {tableName} ({columns})'

Answer 2

You can use join with format:

v = "create table {} ({} varchar(75));".format(tableName, " varchar(75), ".join(flds))