Python生成创建表(Python Generate Create Table)

Python生成创建表(Python Generate Create Table)

我有一个表，其中所有120个字段都有类型varchar（75）。 我编码像这样。

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), "

是否有可能获得单线程？

谢谢！

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!

最满意答案

首先，让我们使用join这样我们就不需要逗号和if 。 而且，虽然我们在它，我们可以循环flds而不是range(len(flds)) ：

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

当然这意味着我们必须在最后添加) ：

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

现在我们可以将这个循环转化为理解：

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

现在，我们可以将其内联到join ：

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

现在，我们有两条线显然可以组合成一条：

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

但这超过80个字符，所以最好把它写成两行。 我可能会这样做：

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

最后，让我们使用一个f字符串而不是与+连接，这样可以使事情变得更短，但更具可读性。

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

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})'