Python操作使用MySQL数据库的实例代码

Python 操作 MySQL

配置

1. win_64
2. Ubuntu14.04
3. Python3.x

pip安装pymysql模块

直接使用pip安装 pip install pymysql

win64上直接在cmd中执行

连接本地数据库

使用模块pymysql连接数据库

    #!/usr/bin/python
    # coding=utf-8
    import pymysql
    # 连接本地数据库
    conn = pymysql.connect(host='localhost', port=3306, user='root', passwd='a123', 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 --')

输出：

    (1, '张三', '男', 24, datetime.date(2017, 3, 29), '13666665555')
    (6, '小刚', '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, 张三
    6, 小刚
    -- end --

可以直接执行sql语句。获得的结果是元组。

增

插入数据

插入一条数据，接上面的代码

    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() # 别忘了提交

添加列

在mobile后面添加一列cash

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

如果要设置默认值

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

删

删除数据

删除 name=秀吉 的数据

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

删除列

删除cash列

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

改

修改数据

更新符合条件的数据

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

事物处理

给某个记录的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("加钱失败了")
    else:
      conn.commit()

直接执行SQL语句，十分方便

代码片段

给数据库添加列

从json中读取需要添加的列名，获取当前2个表中所有的列名

整理得出需要插入的列名，然后将列插入到相应的表中

    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()

将字段字符改变

这里将main_table_keys中的所有字段改为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)

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。