import pymysql
# 連接數(shù)據(jù)庫
conn = pymysql.connect(
  host='127.0.0.1',
  user='root',
  passwd='root',
  port=3306,
  db='test',
  charset='utf8'
)
# 創(chuàng)建一個(gè)游標(biāo)
cursor = conn.cursor()
# 查詢數(shù)據(jù)
sql = "select * from user"
cursor.execute(sql) # 執(zhí)行sql
# 查詢所有數(shù)據(jù)，返回結(jié)果默認(rèn)以元組形式，所以可以進(jìn)行迭代處理
for i in cursor.fetchall():
  print(i)
print('共查詢到：', cursor.rowcount, '條數(shù)據(jù)。')
# 獲取第一行數(shù)據(jù)
result_1 = cursor.fetchone()
print(result_1)
# 獲取前n行數(shù)據(jù)
result_3 = cursor.fetchmany(3)
print(result_3)
cursor.close() # 關(guān)閉游標(biāo)
conn.close() # 關(guān)閉連接

import pymysql
# 連接數(shù)據(jù)庫
conn = pymysql.connect(
  host='127.0.0.1',
  user='root',
  passwd='root',
  port=3306,
  db='test',
  charset='utf8'
)
# 創(chuàng)建一個(gè)游標(biāo)
cursor = conn.cursor()
# 插入數(shù)據(jù)
# 數(shù)據(jù)直接寫在sql后面
sql = "insert into username(id,name) values(%s, %s)" # 注意是%s,不是s%
cursor.execute(sql, [3, '王五']) # 列表格式數(shù)據(jù)
cursor.execute(sql, (4, '馬六')) # 元組格式數(shù)據(jù)
# 數(shù)據(jù)單獨(dú)賦給一個(gè)對(duì)象
sql = "insert into username values(%s,%s)"
data = (5, '老七')
cursor.execute(sql, data) #sql和data之間以","隔開
sql = "insert into username values(%s,'%s')"
data = (6, '小八')
cursor.execute(sql % data) #sql和data之間以"%"隔開，此時(shí)它的sql中注意要給中文字符對(duì)應(yīng)的占位符加上引號(hào)，即"%s",不然會(huì)報(bào)錯(cuò)：unsupported format character
conn.commit()  # 提交，不然無法保存插入或者修改的數(shù)據(jù)(這個(gè)一定不要忘記加上)
cursor.close() # 關(guān)閉游標(biāo)
conn.close() # 關(guān)閉連接

import pymysql
# 連接數(shù)據(jù)庫
conn = pymysql.connect(
  host='127.0.0.1',
  user='root',
  passwd='root',
  port=3306,
  db='test',
  charset='utf8'
)
# 創(chuàng)建一個(gè)游標(biāo)
cursor = conn.cursor()
# 修改數(shù)據(jù)
sql = "update username set name='%s' where id=%s" #注意%s什么時(shí)候加引號(hào)，什么時(shí)候不加
data = ('改名了', 1)
cursor.execute(sql % data)
sql = "update username set name=%s where id=%s"
data = ('也改名了', 2)
cursor.execute(sql, data)
conn.commit()  # 提交，不然無法保存插入或者修改的數(shù)據(jù)
cursor.close() # 關(guān)閉游標(biāo)
conn.close() # 關(guān)閉連接

import pymysql
# 連接數(shù)據(jù)庫
conn = pymysql.connect(
  host='127.0.0.1',
  user='root',
  passwd='root',
  port=3306,
  db='test',
  charset='utf8'
)
# 創(chuàng)建一個(gè)游標(biāo)
cursor = conn.cursor()
# 刪除數(shù)據(jù)
sql = "delete from username where id=%s"
data = (2)
cursor.execute(sql, data)
conn.commit()  # 提交，不然刪除操作不生效
cursor.close() # 關(guān)閉游標(biāo)
conn.close() # 關(guān)閉連接