Question

I have a large list of strings. I need to create a MySQL table where each string in the list is a name of a column (all columns are integers). (I m on python with sqlalchemy).

我审视了一些例子,我认为有必要在图表中明确写出每个栏目。表2. 大型名单的实用性

Is it possible?

增编

Answer 1

您可使用tuple un Packing 。

>>> column_names = [ col1 ,  col2 ,  col3 ]
>>> columns = (Column(name, Integer) for name in column_names)  
>>> table = Table( table_name , metadata, *columns) # unpacks Column instances

And here s an extended example of how you could use this to programmatically create the column names from a list of strings:

>>> column_names = [ col1 ,  col2 ,  col3 ]
>>> columns = (Column(name, Integer) for name in column_names)
>>> table = Table( data , metadata, Column( id , Integer, primary_key=True), *columns)
>>> class Data(object):
...:     def __init__(self, *args):
...:         for name, arg in zip(column_names, args):
...:             setattr(self, name, arg)
...:             
...:
>>> mapper(Data, table)
<<< <Mapper at 0x1026e9910; Data>
>>> data = Data(1, 2, 3)
>>> [x for x in dir(data) if x.startswith( col )] # see if all of our columns are there
<<< [ col1 ,  col2 ,  col3 ] 
>>> data.col3 # great!
<<< 3

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