利用Python對iris數據集進行查詢

利用Python對iris數據集進行查詢

查詢id爲3的行

import pymysql.cursors
connection=pymysql.connect(host='___',user='___',password='___',db='iris',charset='utf8mb4',cursorclass=pymysql.cursors.DictCursor)
try:
    with connection.cursor() as cursor:
        sql= " SELECT * FROM `iris_with_id` WHERE `id`=%s"
        cursor.execute(sql,('3',))
        result=cursor.fetchone()
        print(result)
        print(result['id'])
finally:
    connection.close()

try的主題部分，sql語句，可以根據不同的需要進行改寫。

請複習：

• 選擇petal_width>0.5的所有行：

import pymysql.cursors
connection=pymysql.connect(host='___',user='___',password='___',db='iris',charset='utf8mb4',cursorclass=pymysql.cursors.DictCursor)
try:
    with connection.cursor() as cursor:
        SELECT * FROM `iris_with_id` WHERE `petal_width`>0.5
        result=cursor.fetchall()
        print(result)
finally:
    connection.close()

• 選擇petal_width>0.5的所有行的id

import pymysql.cursors
connection=pymysql.connect(host='___',user='___',password='___',db='iris',charset='utf8mb4',cursorclass=pymysql.cursors.DictCursor)
try:
    with connection.cursor() as cursor:
        SELECT * FROM  `iris_with_id` WHERE `petal_width` >0.5
        result=cursor.fetchall()
        print(len(result))
        for each_r in result:
            print(each_r['id'])
finally:
    connection.close()