Basic SQL database operations, the data written using python the excel database, or read out from the library

First, tell us about some of the basic operation of SQL database:

1 Create 2 Delete 3 4 written update (modify) 5 Select condition

With the above basic operation, you can create and store up a simple database.

 

Release the code to call the python: here is to call dos not as good as the following simple database operation

# - * - Coding: UTF-. 8 - * - 
"" " 
the Created Mon ON. 6 On May 2019 09:59:32 

@author: wenzhe.tian 
" "" 


Import MySQLdb 

# Open Database Connectivity 
DB = MySQLdb.connect ( " localhost " , " the root " , " twz1478963 " , " the TESTDB " , charset = ' UTF8 ' )  
 # using the cursor () method to get the cursor operation 
cursor = db.cursor () 

# if the data table already exists using execute () method to delete table. 
cursor.execute ( ")
print(cursor.fetchone())
cursor.execute("SELECT VERSION()")


# 创建数据表SQL语句
sql = """CREATE TABLE EMPLOYEE (
         FIRST_NAME  CHAR(20) NOT NULL,
         LAST_NAME  CHAR(20),
         AGE INT,  
         SEX CHAR(1),
         INCOME FLOAT );"""

cursor.execute(sql)

### %\　替换
sql = "INSERT INTO EMPLOYEE(FIRST_NAME, \
       LAST_NAME, AGE, SEX, INCOME) \
       VALUES (%s, %s, %s, %s, %s );" % \
       ("'Mac'", " 'Mohan' " , 20, " 'M' " , 9000 ) 
         
         
         
the try :
    # execute sql statement 
   cursor.execute (sql)
    Print (cursor.fetchone ())
    # submitted to the database to perform 
   the db.commit ()
 the except :
    # Case there IS in the any ROLLBACK error 
   db.rollback () 
   
# ##% \ Alternatively 
SQL = " the INSERT the INTO the EMPLOYEE (FIRST_NAME, \ 
       the LAST_NAME, of AGE, SEX, INCOME) \ 
       the VALUES (% S,% S,% S,% S ,% S); " % \ 
       ( " 'John' ", " 'By Will' " , 24-, " 'M' " , 12000 ) 
         
         
         
the try :
    # execute sql statement 
   cursor.execute (sql)
    Print (cursor.fetchone ())
    # submitted to the database to perform 
   the db.commit ()
 the except :
    # Rollback Case there IS the any error in 
   db.rollback () 
   
   
SQL = " the SELECT * the FROM the EMPLOYEE \ 
       the WHERE FIRST_NAME like S% " % ( " '% H_' " ); 
       
'' ' 
the WHERE A and / or B in BETWEEN (A, B ) 
% value represents a plurality of characters, a character _ underlined; 
M%: to be able wildcards, regular expressions, fuzzy intention to query information for the beginning of M.
% M%: indicates that the query contains all the content of M. 
% M_: M represents a query to all the content in the penultimate position of 
'' ' 
       
# DELETE the FROM the EMPLOYEE the WHERE AGE <20        
       
the try :
    # execute SQL statements 
   cursor.execute (SQL)
    # get a list of all the records 
   Results = cursor.fetchall ()
    for Row in results: 
      fname = Row [0] 
      lname = Row [. 1 ] 
      Age = Row [2 ] 
      Sex = Row [. 3 ] 
      Income = Row [. 4 ]
       # printing result 
      Print ( "fname=%s,lname=%s,age=%s,sex=%s,income=%s" % \
             (fname, lname, age, sex, income ))
except:
   print ("Error: unable to fecth data")
   
# 关闭数据库连接
db.close()

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SQL language to write the above code is about to form characters and call the operator interface.

Some examples of storage to put new database excel as the following reference: calling here to_sql dataframe operate Note that the encoding = 'gbk' in Chinese Transformation.

When you create a form name does not need advance written to the database.

# -*- coding: utf-8 -*-
"""
Created on Tue May  7 15:40:23 2019

@author: ext.wenzhe.tian
"""


from sqlalchemy import create_engine
import pandas as pd

host = '127.0.0.1'
port= 3306
db = 'beilixinyuan'
user = 'root'
password = 'twz1478963'

engine = create_engine(str(r"mysql+mysqldb://%s:" + '%s' + "@%s/%s?charset=utf8") % (user, password, host, db))



try:
#   df = pd.read_csv(r'D:\2PHEV_v3.csv',encoding='gbk')
#   读取  
    table='sale_phev'
    sql = "SELECT * FROM "+'%s' %(table)
    df=pd.read_sql(sql,con=engine)
#    写入
#    df.to_sql('sale_ev', con=engine, if_exists='append', index=False)
except Exception as e:

    print(e.message)
    


#The method of deriving 2 
# '' ' 
# the WHERE A and / or B in BETWEEN (A, B) 
# % values represent a plurality of characters, a character _ underlined; 
# M%: to be able wildcard, regular expression represented by meaning fuzzy query information for the beginning of M. 
# % M%: indicates that the query contains all the content of M. 
# % Of M_: M represents a query to all the contents in the penultimate position of the 
# '' ' 
# 
# 
# 
Import MySQLdb
 Import PANDAS PD AS
 # Open Database Connectivity 
DB = MySQLdb.connect ( " localhost " , " the root " , " twz1478963 " , " beilixinyuan " , charset = '' )  
 # Using the cursor () method to get the cursor operation 
Cursor = db.cursor (cursorClass = MySQLdb.cursors.DictCursor) 


SQL = " the SELECT * sale_ev the FROM " 
       

# the DELETE the FROM of AGE the EMPLOYEE the WHERE <20 is        
       
the try :
    # execute SQL statements 
   cursor.execute (SQL)
    # get a list of all the records 
   Results = cursor.fetchall () 
   pd.read_sql (SQL, CON = Engine) 
 
the except :
    Print ( " Error: Unable to fecth the Data " ) 
   
H = list (Results) 
df =pd.DataFrame(h)
del results
del h

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