一、準備數(shù)據(jù)
1、創(chuàng)建數(shù)據(jù)表
-- 創(chuàng)建 "京東" 數(shù)據(jù)庫createdatabasejdcharset=utf8;-- 使用 "京東" 數(shù)據(jù)庫usejd;-- 創(chuàng)建一個商品goods數(shù)據(jù)表createtablegoods(idintunsignedprimarykeyauto_incrementnotnull,namevarchar(150)notnull,? ? cate_namevarchar(40)notnull,? ? brand_namevarchar(40)notnull,? ? pricedecimal(10,3)notnulldefault0,? ? is_showbitnotnulldefault1,? ? is_saleoffbitnotnulldefault0);
2、插入數(shù)據(jù)
-- 向goods表中插入數(shù)據(jù)insertintogoodsvalues(0,'r510vc 15.6英寸筆記本','筆記本','華碩','3399',default,default);insertintogoodsvalues(0,'y400n 14.0英寸筆記本電腦','筆記本','聯(lián)想','4999',default,default);insertintogoodsvalues(0,'g150th 15.6英寸游戲本','游戲本','雷神','8499',default,default);insertintogoodsvalues(0,'x550cc 15.6英寸筆記本','筆記本','華碩','2799',default,default);insertintogoodsvalues(0,'x240 超極本','超級本','聯(lián)想','4880',default,default);insertintogoodsvalues(0,'u330p 13.3英寸超極本','超級本','聯(lián)想','4299',default,default);insertintogoodsvalues(0,'svp13226scb 觸控超極本','超級本','索尼','7999',default,default);insertintogoodsvalues(0,'ipad mini 7.9英寸平板電腦','平板電腦','蘋果','1998',default,default);insertintogoodsvalues(0,'ipad air 9.7英寸平板電腦','平板電腦','蘋果','3388',default,default);insertintogoodsvalues(0,'ipad mini 配備 retina 顯示屏','平板電腦','蘋果','2788',default,default);insertintogoodsvalues(0,'ideacentre c340 20英寸一體電腦 ','臺式機','聯(lián)想','3499',default,default);insertintogoodsvalues(0,'vostro 3800-r1206 臺式電腦','臺式機','戴爾','2899',default,default);insertintogoodsvalues(0,'imac me086ch/a 21.5英寸一體電腦','臺式機','蘋果','9188',default,default);insertintogoodsvalues(0,'at7-7414lp 臺式電腦 linux ）','臺式機','宏碁','3699',default,default);insertintogoodsvalues(0,'z220sff f4f06pa工作站','服務(wù)器/工作站','惠普','4288',default,default);insertintogoodsvalues(0,'poweredge ii服務(wù)器','服務(wù)器/工作站','戴爾','5388',default,default);insertintogoodsvalues(0,'mac pro專業(yè)級臺式電腦','服務(wù)器/工作站','蘋果','28888',default,default);insertintogoodsvalues(0,'hmz-t3w 頭戴顯示設(shè)備','筆記本配件','索尼','6999',default,default);insertintogoodsvalues(0,'商務(wù)雙肩背包','筆記本配件','索尼','99',default,default);insertintogoodsvalues(0,'x3250 m4機架式服務(wù)器','服務(wù)器/工作站','ibm','6888',default,default);insertintogoodsvalues(0,'商務(wù)雙肩背包','筆記本配件','索尼','99',default,default);
-- 查詢類型cate_name為'超級本的商品
select name as 商品名稱,priceas 商品價格from goodswhere cate_name ='超級本';
-- 顯示商品的種類
select distinct cate_namefrom goods; -- 去重
select cate_namefrom goodsgroup by cate_name;-- 分組
-- 查詢每個種類的商品名稱
select cate_name,group_concat(name)from goodsgroup by cate_name;
-- 求所有電腦產(chǎn)品的平均價格，并且保留兩位小數(shù)
select round(avg(price),2)from goods;
-- 顯示每種商品的平均價格
select cate_name,avg(price)from goodsgroup by cate_name;
-- 查詢每種類型的商品中最貴、最便宜、平均價、數(shù)量
select cate_name,max(price),min(price),avg(price),count(*)from goodsgroup by cate_name;
-- 查詢所有價格大于平均價格的商品，并且按價格降序排序
select * from goodswhere price>(select avg(price)from goods)order by pricedesc;
-- 查詢每種類型中最貴的電腦信息
select cate_name,max(price)from goodsgroup by cate_name;
select * from goods;
-- 相當于兩句結(jié)合起來
select * from goods
inner join
? ? (
select
? ? ? ? cate_name,
? ? ? ? max(price)as max_price,
? ? ? ? min(price)as min_price,
? ? ? ? avg(price)as avg_price,
? ? ? ? count(*)from goodsgroup by cate_name
)as goods_new_info
on goods.cate_name=goods_new_info.cate_nameand goods.price=goods_new_info.max_price;
select * from (select cate_name,max(price)as max_pricefrom goodsgroup by cate_name)as g_new
left join goodsas g
on g_new.cate_name=g.cate_nameand g_new.max_price=g.priceorder by g_new.cate_name;
insert into goodsvalues(0,'東哥牌電腦','筆記本','老王','4999',default,default);
-- 創(chuàng)建商品分類表
create table if not exists goods_cates(
id int unsigned primary key auto_increment,
? ? name varchar(40)not null
);
-- 查詢goods商品的種類
select cate_namefrom goodsgroup by cate_name;
insert into goods_cates (name)select cate_namefrom goodsgroup by cate_name;
update goodsas ginner join goods_catesas con g.cate_name=c.name set g.cate_name=c.id;
insert into goods_cates(name)values ('路由器'),('交換機'),('網(wǎng)卡');
insert into goods (name,cate_id,brand_id,price)
values('LaserJet Pro P1606dn 黑白激光打印機', 12, 4,'1849');
alter table goods
change cate_namecate_id int unsigned not null;
alter table goodsadd foreign key (cate_id)references goods_cates(id);-- 外鍵關(guān)聯(lián)
delete from goodswhere id=23;
-- 創(chuàng)建商品品牌表
create table if not exists goods_brands(
id int unsigned primary key auto_increment,
? ? name varchar(40)not null
);
select brand_namefrom goodsgroup by brand_name;
insert into goods_brands (name)select brand_namefrom goodsgroup by brand_name;
update goodsas ginner join goods_brandsas bon g.brand_name=b.name set g.brand_name=b.id;
alter table goods
change brand_namebrand_id int unsigned not null;
alter table goodsadd foreign key (brand_id)references goods_brands(id);-- 外鍵關(guān)聯(lián)
insert into goods (name,cate_id,brand_id,price)
values('LaserJet Pro P1606dn 黑白激光打印機', 2, 100,'1849');
-- 創(chuàng)建品牌表
create table goods_brands (
id int unsigned primary key auto_increment,
? ? name varchar(40)not null)select brand_nameas name from goodsgroup by brand_name;
update goodsas ginner join goods_brandsas bon g.brand_name=b.name set g.brand_name=b.id;
alter table goods
change brand_namebrand_id int unsigned not null;
alter table goodsadd foreign key (brand_id)references goods_brands(id);
-- 取消外鍵
alter table goodsdrop foreign key goods_ibfk_1;
alter table goodsdrop foreign key goods_ibfk_2;
# 在python3中使用 數(shù)據(jù)庫
# python2? import MySQLdb
import pymysql
'''
'''
from pymysqlimport connect
# 創(chuàng)建connection連接
conn = connect(host='localhost',port=3306,database='wn',user='root',password='root',charset='utf8')
# 獲取cursor對象
cursor = conn.cursor()
count = cursor.execute("select * from goods;")
print('查詢到%d條數(shù)據(jù)'%count)
# print(cursor.fetchone())
# print(cursor.fetchone())
# print(cursor.fetchone())
# print(cursor.fetchone())
#
# print(cursor.fetchmany())# 取一條
# print(cursor.fetchmany(3))# 傳幾條取幾條
#
# print(cursor.fetchall()) #取所有
line_content = cursor.fetchone()
print(line_content)
print(line_content[0])
print(line_content[1])
print(line_content[2])
for tempin line_content:
print(temp)
lines = cursor.fetchmany(5)
for tempin lines:
print(temp)
# 關(guān)閉cursor對象
cursor.close()
conn.close()
# print(cursor.fetchone(),'--------->')
# count = cursor.execute("select * from goods;")
# 數(shù)據(jù)庫關(guān)閉之后不能再調(diào)用代碼
