XI. Database and python

And a database .python

1. Connect database

Import pymysql 
 # # 01 connect to the database 
#      Parameter 1: mysql hostname 192.168.245.1 
#      Parameter 2: username 
#      Parameter 3: password 
#      Parameter 4: name of the connected database 
DB = pymysql.connect ( " localhost " , " the root " , " root " , " a " ) 

# 02 objects to create a cursor 
cursor = db.cursor () 

# 03 construct sql statement 
sql = " the SELECT Version () " 

# 04 executed sql statement 
cursor.execute (sql) 

# 05 get return data
= Data cursor.fetchone ()
 Print (Data)                   # ( '5.5.47',) MySQL version number 
# 06 is disconnected 
cursor.close ()
 # 07 off 
db.Close ()

2. Create a table

Import pymysql 

db = pymysql.connect ( " localhost " , " root " , " root " , " db1 " ) 

# 02 objects to create a cursor 
cursor = db.cursor () 

# Check the table exists, if there is deleted 
cursor.execute ( " drop the table IF EXISTS info " ) 

# built table 
sql = ' the Create the table info (the above mentioned id int AUTO_INCREMENT Primary Key, Money int not null) ' 

# execute sql statement table 
cursor.execute (sql)

3. Insert Data

Import pymysql 
DB = pymysql.connect ( " localhost " , " the root " , " the root " , " A " ) 

# 02 to create a cursor object 
cursor = db.cursor () 

# insert data 
SQL = ' INSERT INTO BB values (0, 5000) ' 
the try : 
    cursor.execute (SQL) 
the except : 

    # If the commit fails go back to the last data 
    db.rollback () 

# 06 off 
cursor.close ()
 # 07 Close 
db.close ()

4. Update Data

Import pymysql 


# # 01 connect to the database 
#      Parameter 1: mysql hostname 
#      Parameter 2: username 
#      Parameter 3: password 
#      Parameter 4: name of the connected database 

DB = pymysql.connect ( " localhost " , " the root " , " the root " , " a " ) 

# 02 to create a cursor object 
cursor = db.cursor () 

# update data 
SQL = ' update BB SET = 6662 WHERE ID = Money. 1 ' 
the try : 

    the cursor.execute (SQL) 

the except :

    # If the commit fails go back to the last data 
    db.rollback () 

# 06 off 
cursor.close () 

# 07 Close 
db.close ()

5. Delete Data

Import pymysql 


# # 01 connect to the database 
#      Parameter 1: mysql hostname 
#      Parameter 2: username 
#      Parameter 3: password 
#      Parameter 4: name of the connected database 

DB = pymysql.connect ( " localhost " , " the root " , " the root " , " a " ) 

# 02 objects to create a cursor 
cursor = db.cursor () 

# delete data 
SQL = ' the delete from the WHERE Money bb = 6662 ' 

the try : 
    cursor.execute (SQL) 
the except : 

    #If the commit fails go back to the last data 
    db.rollback () 


# 06 off 
cursor.close () 

# 07 Close 
db.close ()

6. Find data

"" " 
Fetchone () function: get the next result set result set is an object 

fetchall () function: to receive full return line 

rowcount: is a read-only property returns the execute () method affect the number of rows (that is, only you checked how many pieces of data)

 "" " 

Import pymysql 


# # 01 connect to the database 
#      parameter 1: mysql hostname 
#      parameter 2: username 
#      parameter 3: password 
#      parameter 4: name of the connected database 

DB = pymysql.connect ( " localhost " , " root " , " root " , " a " ) 

# 02 objects to create a cursor 
cursor = db.Cursor () 

# insert data 
sql =' SELECT * WHERE Money from CC> 400 ' 

the try : 
    the cursor.execute (SQL) 
    reslist = cursor.fetchall ()   # receive all return line 
    for Row in reslist:
         Print (Row [0], Row [. 1 ]) 


            # . 3 500 
            # 4 600 
            # 5 700 

the except : 

    # If the commit fails go back to the last data 
    db.rollback () 

# 06 off 
cursor.close () 

# 07 Close 
db.close ()

7. The data package CRUD

Import pymysql 

class My_Sql (): 
   
    DEF  the __init__ (Self, Host, User, the passwd, dbName): 

        self.host = Host 
        self.user = User 
        self.passwd = the passwd 
        self.dbName = dbName 

    DEF Connet (Self): 
        self.db = pymysql.connect (self.host, self.user, self.passwd, self.dbName) 
        self.cursor = self.db.cursor ()    


    DEF Close (Self): 
         self.cursor.close () 
         self.db.close () 
     
 # fetchone () query functions: to get the next result set is a result set objects    
    DEF get_one (Self, SQL): 

         RES = None
          the try : 
            self.connet () 
            self.cursor.execute (SQL) 
            RES = self.cursor.fetchone () 
            self.close () 
         the except :
             Print ( " Query failed " )
          return RES 

# or fetchall () query function: to receive all return lines 
    DEF get_all (Self, SQL): 

         RES = ()
          the try : 
            self.connet () 
            self.cursor.execute (SQL) 
            RES=self.cursor.fetchall()
            self.close()
         except:
            print("查询失败")
         return res


    def insert(self,sql):
        return self._edit(sql)

        
    def update(self,sql):
        return self._edit(sql)


    def delete(self,sql):
        return self.__edit(sql)


    def __edit(self,sql):
        count=0
        try:
            self.connet()
            count=self.cursor.execute(sql)
            self.db.commit()
            self.close()
        except :
            print("提交失败了")
            self.db.rollback()
        return count