Python 操作 MySQL數(shù)據(jù)庫

更新時間：2020年09月18日 15:03:28 作者：RF-Dev

這篇文章主要介紹了Python 如何操作 MySQL，幫助大家更好的理解和使用python，感興趣的朋友可以了解下

開發(fā)環(huán)境與配置

win_x64
Ubuntu14.04
Python3.x

pip安裝pymysql模塊

直接使用pip安裝 pip install pymysqlwin64上直接在cmd中執(zhí)行

連接本地?cái)?shù)據(jù)庫

使用模塊pymysql連接數(shù)據(jù)庫

本地?cái)?shù)據(jù)庫相關(guān)配置請參閱： http://rustfisher.github.io/2017/02/25/backend/MySQL_install/

#!/usr/bin/python
# coding=utf-8
import pymysql

# 連接本地?cái)?shù)據(jù)庫
conn = pymysql.connect(host='localhost', port=3306, user='root', passwd='yourpwd', db='samp_db1', charset='utf8')
cursor = conn.cursor()
cursor.execute('select * from bigstu')
for row in cursor.fetchall():
  print(row)

# 查
cursor.execute('select id, name from bigstu where age > 22')
for res in cursor.fetchall():
  print(str(res[0]) + ", " + res[1])

cursor.close()
print('-- end --')

輸出：

(1, '張三', '男', 24, datetime.date(2017, 3, 29), '13666665555')
(6, '小剛', '男', 23, datetime.date(2017, 3, 11), '778899888')
(8, '小霞', '女', 20, datetime.date(2017, 3, 13), '13712345678')
(12, '小智', '男', 21, datetime.date(2017, 3, 7), '13787654321')
1, 張三
6, 小剛
-- end --

可以直接執(zhí)行sql語句。獲得的結(jié)果是元組。

sql相似條件查詢

SELECT * FROM anindex.subject_basic_table where season_id having '2018';

增

插入數(shù)據(jù)

插入一條數(shù)據(jù)，接上面的代碼

insertSql = "insert into bigstu (name, sex, age, mobile) values ('%s','%s',%d,'%s') "
xiuji = ('秀吉', '男', 15, '13400001111')
cursor.execute(insertSql % xiuji)
conn.commit() # 別忘了提交

添加列

在mobile后面添加一列cash

addCo = "alter table bigstu add cash int after mobile"
cursor.execute(addCo)

如果要設(shè)置默認(rèn)值

addCo = "alter table bigstu add cash int default 0 after mobile"
cursor.execute(addCo)

刪

刪除數(shù)據(jù)

刪除 name=秀吉的數(shù)據(jù)

deleteSql = "delete from bigstu where name = '%s'"
cursor.execute(deleteSql % '秀吉')

刪除列

刪除cash列

dropCo = "alter table bigstu drop cash"
cursor.execute(dropCo)

改

修改數(shù)據(jù)

更新符合條件的數(shù)據(jù)

updateSql = "update bigstu set sex = '%s' where name = '%s'"
updateXiuji = ('秀吉', '秀吉') # 秀吉的性別是秀吉
cursor.execute(updateSql % updateXiuji)
conn.commit()

事物處理

給某個記錄的cash增加

table = "bigstu"
addCash = "update " + table + " set cash = cash + '%d' where name = '%s'"
lucky = (1000, "秀吉")

try:
  cursor.execute(addCash % lucky)
except Exception as e:
  conn.rollback()
  print("加錢失敗了")
else:
  conn.commit()

直接執(zhí)行SQL語句，十分方便

代碼片段

給數(shù)據(jù)庫添加列

從json中讀取需要添加的列名，獲取當(dāng)前2個表中所有的列名
整理得出需要插入的列名，然后將列插入到相應(yīng)的表中

import pymysql
import json
import os
import secureUtils

mapping_keys = json.load(open("key_mapping_db.json", "r"))
db_keys = [] # json中所有的key

for k in mapping_keys.values():
  db_keys.append(k)

conn = pymysql.connect(host='localhost', port=3306, user='root',
            passwd='*****', db='db_name', charset='utf8')

cursor = conn.cursor()
table_main = "table_main"
main_table_keys = [] # 主表的列名
cursor.execute("show columns from " + table_main)
for row in cursor.fetchall():
  main_table_keys.append(row[0])

staff_table_keys = []
cursor.execute("show columns from table_second")
for row in cursor.fetchall():
  staff_table_keys.append(row[0])

need_to_insert_keys = []
for k in db_keys:
  if k not in staff_table_keys and k not in main_table_keys and k not in need_to_insert_keys:
    need_to_insert_keys.append(k)

print("need to insert " + str(len(need_to_insert_keys)))
print(need_to_insert_keys)
for kn in need_to_insert_keys:
  print("add key to db " + kn)
  cursor.execute("alter table staff_table add " + kn +" text")

conn.close()

將字段字符改變

這里將main_table_keys中的所有字段改為utf8

# change column character set to utf8
for co in main_table_keys:
  change_sql = "alter table " + table_main + " modify " + co + " text character set utf8"
  print(change_sql)
  cursor.execute(change_sql)

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