Method of Python Operating PostgreSql Database of Basic Addition Deletion Modification and Search

Directory Python operation PostgreSql database (basic addition, deletion and modification) psycopg2 simple addition, deletion and modification connection, addition, deletion and supplement, and the added fields have time format

Python operation PostgreSql database (basic addition, deletion and modification)

Of course, the fastest way to operate the database is to use SQL language directly to operate the database, but occasionally we will encounter the situation of operating the database in the code. We may use ORM class library to operate the NC library, but when a large amount of data needs to be operated, ORM data is too slow. In python, in such a situation, I recommend using psycopg2 Operation postgresql Database

psycopg2

Official document portal: http://initd.org/psycopg/docs/index. html

Simple addition, deletion and revision

Connect

Connect to pg and create a table

PG_SQL_LOCAL = {
 'database': 'postgres',
 'user': 'postgres',
 'password': "8dsa581",
 # 'host':'10.27.78.1',
 'host': 'localhost'
}

def connectPostgreSQL():
 conn = psycopg2.connect(**PG_SQL_LOCAL)
 print('connect successful!')
 cursor = conn.cursor()
 cursor.execute('''
 create table public.members(
 id integer not null primary key,
 name varchar(32) not null,
 password varchar(32) not null,
 singal varchar(128)
 )''')
 conn.commit()
 conn.close()
 print('table public.member is created!')

Increase

Added data of 1 article and 1 article

def insertOperate():
 conn = psycopg2.connect(**PG_SQL_LOCAL)
 cursor = conn.cursor()
 cursor.execute("insert into public.member(id,name,password,singal)\
values(1,'member0','password0','signal0')")
 cursor.execute("insert into public.member(id,name,password,singal)\
values(2,'member1','password1','signal1')")
 cursor.execute("insert into public.member(id,name,password,singal)\
values(3,'member2','password2','signal2')")
 cursor.execute("insert into public.member(id,name,password,singal)\
values(4,'member3','password3','signal3')")
 row = conn.fetchone()
 print(row)
 conn.commit()
 conn.close()

 print('insert records into public.memmber successfully')

Check

fetchall () gets all data once fetchmany () Extracts 2000 pieces of data once (using server-side cursors)

def selectOperate():
 conn = psycopg2.connect(**PG_SQL_LOCAL)
 cursor = conn.cursor()
 cursor.execute("select id,name,password,singal from public.member where id>2")
 # rows = cursor.fetchall()
 # for row in rows:
 # print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3],)

 while True:
 rows = cursor.fetchmany(2000)
 if not rows:
  break
 for row in rows:
  # print('id=', row['id'], ',name=', row['name'], ',pwd=', row['pwd'], ',singal=', row['singal'],)
  rid,name,pwd,singal = row
  print(rid,name,pwd,singal)
  # print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3], )
 conn.close()

Change

Update data

def updateOperate():
 conn = psycopg2.connect(**PG_SQL_LOCAL)
 cursor=conn.cursor()
 result = cursor.execute("update public.member set name='member X' where id=3")
 print(result)
 conn.commit()
 print("Total number of rows updated :", cursor.rowcount)

 cursor.execute("select id,name,password,singal from public.member")
 rows=cursor.fetchall()
 for row in rows:
 print('id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n')
 conn.close()

Delete

Delete data

def deleteOperate():
 conn = psycopg2.connect(**PG_SQL_LOCAL)
 cursor = conn.cursor()

 cursor.execute("select id,name,password,singal from public.member")
 rows = cursor.fetchall()
 for row in rows:
 print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3], '\n')

 print('begin delete')
 cursor.execute("delete from public.member where id=2")
 conn.commit()
 print('end delete')
 print("Total number of rows deleted :", cursor.rowcount)

 cursor.execute("select id,name,password,singal from public.member")
 rows = cursor.fetchall()
 for row in rows:
 print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3], '\n')
 conn.close()

Added, added fields with time format

With time format, you only need to pass in the string in time format ('2017-05-27'), which will be automatically recognized by PG

cur.execute("INSERT INTO Employee "
  "VALUES('Gopher', 'China Beijing', 100, '2017-05-27')")
#  Query data 
cur.execute("SELECT * FROM Employee")
rows = cur.fetchall()
for row in rows:
 print('name=' + str(row[0]) + ' address=' + str(row[1]) +
  ' age=' + str(row[2]) + ' date=' + str(row[3]), type(row[3]))

 #  Insert data 
 sql = """INSERT INTO Employees VALUES(%s, %s, %s,%s) """
 var = []
 var.append([row[0], row[1], row[2], row[3]])
 cur.executemany(sql, var)

#  Commit transaction 
conn.commit()

#  Close the connection 
conn.close()