import pandas as pd df1=pd.read_csv('items.csv') df2=pd.read_csv('signup.csv') df=pd.merge(df1, df2, on='item_id', how='left') df.fillna(0) d=df.groupby('item_name')['name'].count() print(d)

import pandas as pd df=pd.read_csv('Nowcoder.csv',sep=',') df1=df.groupby('Level')['Name'].count() print(df1[df1>5])

import pandas as pd df=pd.read_csv('Nowcoder.csv',sep=',') res=df.groupby(['Level','Language'])['Name'] res1=res.count() print(res1)

import pandas as pd df=pd.read_csv('Nowcoder.csv',sep=',') df1=df.groupby('Graduate_year')['Achievement_value'].max() print(df1)

import pandas as pd df=pd.read_csv('nowcoder.csv',sep=',') df1=df.groupby('result').size() print(df1)

import pandas as pd df=pd.read_csv('nowcoder.csv',sep=',') df['year-month-day']=pd.to_datetime(df['date']).dt.date df1=df['question_id'].groupby([df['result'], df['year-month-day']]).count() print(df1)

import pandas as pd df = pd.read_csv("Nowcoder.csv", sep=",") df2=df[df.Num_of_exercise>10] print(round(df2.Num_of_exercise/df2.Number_of_submissions,3).max())

import pandas as pd df = pd.read_csv("Nowcoder.csv", sep=",") grouped = df[df.Level==7]["Achievement_value"] sum_value=df.Achievement_value.sum() print(grouped/sum_value)

import pandas as pd Nowcoder = pd.read_csv('Nowcoder.csv',sep=',',dtype=object) print(Nowcoder.loc[Nowcoder['Language']=='Python','Achievement_value'])

select V.vend_id,count(P.prod_id) prod_ids from Vendors V left join Products P on V.vend_id=P.vend_id group by V.vend_id order by V.vend_id

select cust_name,order_num from Customers C left join Orders O on C.cust_id=O.cust_id order by cust_name

select cust_id,total_ordered from( select order_num,sum(quantity*item_price) total_ordered from OrderItems group by order_num order by total_ordered desc )tmp join Orders O on tmp.order_num=O.order_num

select cust_id from OrderItems OI join Orders O on OI.order_num=O.order_num where OI.item_price >=10

select order_num from( select order_num, sum(quantity)over(partition by order_num) sum from OrderItems order by order_num )tmp where sum>=100