React Native Developer

Friday, December 28, 2018

PYTHON DATABASE CONNRCTIVITY


Creating Database Table

import MySQLdb
# Open database connection
db = MySQLdb.connect("localhost",“root",“root","TESTDB" )

# prepare a cursor object using cursor() method
cursor = db.cursor()

# Drop table if it already exist using execute() method.
cursor.execute("DROP TABLE IF EXISTS EMPLOYEE")

# Create table as per requirement
sql = """CREATE TABLE EMPLOYEE (
         FIRST_NAME  CHAR(20) NOT NULL,
         LAST_NAME  CHAR(20),
         AGE INT, 
         GENDER CHAR(1),
         INCOME FLOAT )"""
cursor.execute(sql)

# disconnect from server
db.close()

******************************************************************************************************************************************************************

INSERT Operation
import MySQLdb

# Open database connection
db = MySQLdb.connect("localhost","root","root","TESTDB" )

# prepare a cursor object using cursor() method
cursor = db.cursor()

# Prepare SQL query to INSERT a record into the database.
sql = """INSERT INTO EMPLOYEE(FIRST_NAME,
         LAST_NAME, AGE, GENDER, INCOME)
         VALUES ('Mac', 'Mohan', 20, 'M', 2000)"""

try:
   # Execute the SQL command
   cursor.execute(sql)
   # Commit your changes in the database
   db.commit()
except:
   # Rollback in case there is any error
   db.rollback()

# disconnect from server
db.close()

******************************************************************************************************************************************************************

Above example can be written as follows to create SQL queries dynamically −
import MySQLdb

# Open database connection
db = MySQLdb.connect("localhost","root","root","TESTDB" )

# prepare a cursor object using cursor() method
cursor = db.cursor()

# Prepare SQL query to INSERT a record into the database.
sql = "INSERT INTO EMPLOYEE(FIRST_NAME, \
       LAST_NAME, AGE, GENDER, INCOME) \
       VALUES ('%s', '%s', '%d', '%c', '%d' )" % \
       ('Mac', 'Mohan', 20, 'M', 2000)

try:
   # Execute the SQL command
   cursor.execute(sql)
   # Commit your changes in the database
   db.commit()
except:
   # Rollback in case there is any error
   db.rollback()

# disconnect from server
db.close()

******************************************************************************************************************************************************************

select operation
import MySQLdb

# Open database connection
db = MySQLdb.connect("localhost","root","root","TESTDB" )

# prepare a cursor object using cursor() method
cursor = db.cursor()

sql = "SELECT * FROM EMPLOYEE \
       WHERE INCOME > '%d'" % (1000)
try:
               # Execute the SQL command
   cursor.execute(sql)
   # Fetch all the rows in a list of lists.
   results = cursor.fetchall()
   for row in results:
      fname = row[0]
      lname = row[1]
      age = row[2]
      Gender= row[3]
      income = row[4]
      # Now print fetched result
      print "fname=%s,lname=%s,age=%d,gender=%s,income=%d" % \
             (fname, lname, age, gender, income )
except:
   print "Error: unable to fecth data"

# disconnect from server
db.close()

******************************************************************************************************************************************************************

update Operation
import MySQLdb

# Open database connection
db = MySQLdb.connect("localhost","root","root","TESTDB" )

# prepare a cursor object using cursor() method
cursor = db.cursor()

# Prepare SQL query to UPDATE required records
sql = "UPDATE EMPLOYEE SET AGE = AGE + 1
                          WHERE gender= '%c'" % ('M')
try:
   # Execute the SQL command
   cursor.execute(sql)
   # Commit your changes in the database
   db.commit()
except:
   # Rollback in case there is any error
   db.rollback()

# disconnect from server
db.close()

******************************************************************************************************************************************************************

DELETE Operation

import MySQLdb

# Open database connection
db = MySQLdb.connect("localhost",“root",“root","TESTDB" )

# prepare a cursor object using cursor() method
cursor = db.cursor()
# Prepare SQL query to DELETE required records
sql = "DELETE FROM EMPLOYEE WHERE AGE > '%d'" % (20)
try:
   # Execute the SQL command
   cursor.execute(sql)
   # Commit your changes in the database
   db.commit()
except:
   # Rollback in case there is any error
   db.rollback()

# disconnect from server
db.close()



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