使用python从数据库中的多个表中提取多个值

Question

I have a python list which has multiple lists inside having tables and variables in those tables. Example:

list = [ [ table1, var1 ], [ table2,var2,var3,var4 ], [ table3,var5,var6 ] ] .

Can a single SQL query be written in python to extract the data from all the given tables.

In SQL we will write something like this

SELECT table1.var1, table2.var2, table2.var3 FROM table1, table2.

But in python I am facing difficulty as at a time we can have access to only one element, ex: list[0][1],list[1][0] etc.

Answer 1

You can access the list elements dynamically. Assuming your list stores strings and you want to output a string:

for tablelist in list:
    for var in tablelist[1:]:
        print(tl[0] + '.' + var)

Or using a list comprehension:

[tablelist[0] + '.' + var for tablelist in list for var in tablelist[1:]]

To create a string containing the SQL statement from your question:

var_accesses = [tablelist[0] + '.' + var for tablelist in list for var in tablelist[1:]]
var_accesses_string = ', '.join(var_accesses)
tables = [tablelist[0] for tablelist in list]
tables_string = ', '.join(tables)
sql_query = 'SELECT {} FROM {}'.format(var_accesses_string, tables_string)