pymysql -转自https://www.cnblogs.com/chenhaiming/p/9883349.html#undefined

PyMysql的几个重要方法

1. connect函数：连接数据库，根据连接的数据库类型不同，该函数的参数也不相同。connect函数返回Connection对象。
2. cursor方法：获取操作数据库的Cursor对象。cursor方法属于Connection对象。
3. execute方法：用于执行SQL语句，该方法属于Cursor对象。
4. commit方法：在修改数据库后，需要调用该方法提交对数据库的修改，commit方法属于Cursor对象。
5. rollback方法：如果修改数据库失败，一般需要调用该方法进行数据库回滚操作，也就是将数据库恢复成修改之前的样子

6. from pymysql import *
   import json
   
   def connectDB():
       db = connect('127.0.0.1','root','password','databasename')
       return db
   db = connectDB()
   
   def creatTable(db):
       cursor = db.cursor()
       sql = '''
       CREATE TABLE Persons
           (
               id INT PRIMARY KEY NOT NULL,
               name TEXT NOT NULL,
               age INT NOT NULL,
               address CHAR(50),
               salary REAL
           );
       '''
       try:
           cursor.execute(sql)
           db.commit()
           return True
       except:
           db.rollback()
       return False
   
   def insertRecords(db):
       cursor = db.cursor()
       try:
           cursor.execute('DELETE FROM persons')
           cursor.execute("INSERT INTO persons(id,name,age,address,salary)\
                          VALUES(1,'Paul',32,'California',2000.00)");
           cursor.execute("INSERT INTO persons(id,name,age,address,salary)\
                              VALUES(2,'Allen',25,'Texas',3000.00)");
           cursor.execute("INSERT INTO persons(id,name,age,address,salary)\
                              VALUES(3,'Teddy',23,'Norway',2500.00)");
           cursor.execute("INSERT INTO persons(id,name,age,address,salary)\
                              VALUES(4,'Mark',19,'Rich',5000.00)");
           db.commit()
           return True
       except Exception as e:
           print(e)
           db.rollback()
       return False
   
   def selectRecords(db):
       cursor = db.cursor()
       sql = 'SELECT name,age,address,salary FROM Persons ORDER BY age DESC'
       cursor.execute(sql)
       results = cursor.fetchall()
       print(results)
       fields = ['name','age','address','salary']
       records = []
       for row in results:
           records.append(dict(zip(fields,row)))
       return json.dumps(records)
   
   if creatTable(db):
       print('成功创建Persons表')
   else:
       print('persons表已经存在')
   
   if insertRecords(db):
       print('成功插入数据')
   else:
       print('插入记录失败')
   
   print(selectRecords(db))
   db.close()