python 连接oracle -- sqlalchemy及cx_Oracle的使用详解

　　python连接oracle -- sqlalchemy

import cx_Oracle as orcl
import pandas as pd
from sqlalchemy import create_engine

# 数据库连接
db = create_engine('oracle://qmcb:qmcb@localhost:1521/tqmcbdb')

#查询
sql_select = ''' ...'''
df = pd.read_sql_query(sql_select, db)

#执行
db.execute('truncate table {}'.format(ttb))

#保存
df.to_sql()  #太慢

#插入
conn = db.raw_connection()
cursor = conn.cursor()
col = ', '.join(df.columns.tolist())
s = ', '.join([':'+str(i) for i in range(1, df.shape[1]+1)])
sql = 'insert into {}({}) values({})'.format(ttb, col, s)
cursor.executemany(sql, df.values.tolist())
conn.commit()
cursor.close()

　　python连接oracle -- cx_Oracle

cx_oracle 使用

oracle 数据库表字段的缺失值统计 -- 基于python

cx_Oracle模块的安装和使用  看下连接oracle的各种方式

import cx_Oracle as orcl

#定义oracle连接
orcl.connect('load/123456@localhost/ora11g')
orcl.connect('username','password','host:port/orcl')
tnsname = orcl.makedsn('host', 'port', 'sid')
db = orcl.connect('username', 'password', tnsname)

#数据库参数输出
db.autocommit = False  # 关闭自动提交
orcl.clientversion()
db.version
db.ping()
db.username
db.password
db.dsn   #dsn=data source name
db.tnsentry
cursor.rowcount

#定义游标
#orcl.Cursor(db)
cursor = db.cursor()

#查询数据 + 执行代码（如建表，清空表）
sql = "SELECT ENAME, trunc(SAL,0) FROM EMP WHERE deptno = :deptno and sal > :value"
cursor.execute(sql, deptno = 30, value = 1000)
dict1 = {'deptno':30, 'sal':3000}
cursor.execute(sql, dict1)
cursor.execute(sql)

#
cursor.fetchone()
cursor.fetchall()
cursor.fetchmany(10) #查10条数据

#插入数据
#mysql自带load data infile 'D:/../...txt' into table user(var1, ., .)
cursor.execute('insert into demo(v) values(:1)',['nice'])
data = [['a',1], ['b',2], ...]
cursor.executemany(sql, data)

#查询列名
columns = [i[0] for i in cursor.description]

#出错回滚  -- 一般如插入数据时出错回滚， try:...except:db.rollback()
db.rollback()

#关闭数据库
cursor.close()
db.close()

　　定义ConnectOracle对象

import cx_Oracle as orcl
class ConnectOracle:
    #scott xx 192.168.32.200 1521 oracle
    #sqlplus, system as sysdba, select instance_name from  V$instance;
    #oracle://qmcbrt:qmcbrt@localhost:1521/tqmcbdb
    #cx_Oracle.connection('hr', 'hrpwd', 'localhost:1521/XE')
    ##cx_Oracle.connection('qmcb:qmcb@localhost:1521/tqmcbdb')
    def __init__(self, username, passwd, host, port='1521', sid='oracle'):
        # dsn = data source name
        self.login = {}
        self.db = None
        self.cursor = None
        self.login['username'] = username
        self.login['passwd'] = passwd
        self.login['dsn'] = orcl.makedsn(host, port, sid)
        print(orcl.clientversion())

    def connect_oracle(self):
        try:
            #orcl.connect('load/123456@localhost/ora11g')
            #orcl.connect('username','password','host/orcl')
            self.db = orcl.connect(self.login['username'], self.login['passwd'], self.login['dsn'])  # 登录内搜数据库
            self.db.autocommit = False  # 关闭自动提交
            #orcl.Cursor(self.db)
            self.cursor = self.db.cursor()  # 设置cursor光标
            #print(self.db.dsn)
            #print(self.db.password)
            #print(self.db.ping())
            #print(self.db.tnsentry)
            #print(self.db.username);
            #print(self.db.version)
            #print(self.cursor.rowcount)
            return True
        except:
            print('can not connect oracle')
            return False

    def close_oracle(self):
        self.cursor.close()
        self.db.close()

    def select_oracle(self, sql, size=0, params=None):
        if self.connect_oracle():
            if params:
                # 执行多条sql命令
                # results = cur.executemany("select field from table where field = %s", ('value1', 'value2', 'value3'))
                #sql = "SELECT ENAME, trunc(SAL,0) FROM EMP \
                #           WHERE deptno = :deptno and sal > :value"
                #cursor.execute(sql, deptno = 30, value = 1000);
                #params = {'deptno':30, 'sal':3000}
                #cur.execute(sql, params)
                self.cursor.executemany(sql, params)
            else:
                self.cursor.execute(sql)
            if size:
                content = self.cursor.fetchmany(size)
            else:
                content = self.cursor.fetchall()

            # 字段名
            #ss = sql.lower()
            #find默认查找从左向右第一个位置
            #string = sql[ss.find('select'), ss.find('from')]
            columns = [i[0] for i in self.cursor.description]
            self.close_oracle()
            #if len(content)==1:
            #    return pd.Series(content[0], index=columns)
            return pd.DataFrame(content, columns=columns)
        return False

    def insert_oracle(self, sql, data=None):
        try:
            self.connect_oracle()
            if data:
                # 批量插入, [(),..]、((),..)
                # mysql自带load data infile 'D:/../...txt' into table user(var1, ., .)
                #self.cursor.execute('insert into demo(v) values(:1)',['nice'])
                self.cursor.executemany(sql, data)
            else:
                self.cursor.execute(sql, data)
        except:
            print("insert异常")
            self.db.rollback()  # 回滚
        finally:
            self.db.commit()  # 事务提交
            self.close_oracle()

　　定义读取oracle函数

def read_db(orcl_engien, ftb, snum, enum):
    db = create_engine(orcl_engien)  #不需要close()
    query_sql = '''
        select *
        from {}
        where
        row_num > {} and
        row_num <= {} and
        is_normal='1' and
        is_below_16='0' and
        is_xs='0' and
        is_cj='0' and
        is_bzsw='0' and
        is_dc='0' and
        is_px='0'
        '''.format(ftb, snum, enum)
    return pd.read_sql_query(query_sql, db)

　　定义connectOracle

class ConnectOracle:
    def __init__(self, username, passwd, host, port='1521', sid='oracle'):
        # dsn = data source name
        self.login = {}
        self.db = None
        self.cursor = None
        self.login['username'] = username
        self.login['passwd'] = passwd
        self.login['dsn'] = orcl.makedsn(host, port, sid)
        print(orcl.clientversion())

    def connect(self):
        try:
            #orcl.connect('load/123456@localhost/ora11g')
            self.db = orcl.connect(self.login['username'], self.login['passwd'], self.login['dsn'])  # 登录内搜数据库
            self.db.autocommit = False  # 关闭自动提交
            self.cursor = self.db.cursor()  # 设置cursor光标
            return True
        except Exception as e:
            print(e)
            return False

    def close(self):
        self.cursor.close()
        self.db.close()

    def execute(self, sql, params=None):
        try:
            if params:
                self.cursor.execute(sql, params)
            else:
                self.cursor.execute(sql)
            return True
        except Exception as e:
            print(e)
            self.db.rollback()
            return False

    def select(self, sql, size=0, params=None):
        if self.connect():
            if self.execute(sql):
                if size:
                    data_list = self.cursor.fetchmany(size)
                else:
                    data_list = self.cursor.fetchall()
                columns = [i[0].lower() for i in self.cursor.description]
                #if len(content)==1:
                #    return pd.Series(content[0], index=columns)
                df = pd.DataFrame(data_list, columns=columns)
                return df
            else:
                print('代码执行错误')
            self.close()
        else:
            print('数据库连接错误')
            return None

    def insert(self, sql, data=None):
        if self.connect():
            try:
                if data:
                    if isinstance(data[0], (list,tuple,)):
                        self.cursor.executemany(sql, data)
                    else:
                        self.cursor.execute(sql, data)
                else:
                    self.cursor.execute(sql)
            except Exception as e:
                print(e)
                print("insert异常")
                self.db.rollback()  #回滚
            finally:
                self.db.commit()  #事务提交
                self.close()
        else:
            print('数据库连接错误')

　　定义插入oracle函数

import retry

#backoff=1, jitter=0, , logger=retry.logging
@retry.retry(exceptions=Exception, tries=5, delay=5, backoff=1, max_delay=10)
def insert_db(data, orcl_engien, ttb):
    # dtyp = {col:types.VARCHAR(df[col].str.len().max())
    #    for col in df.columns[df.dtypes == 'object'].tolist()}
    # 太慢！！
    #dtyp = {'aac147':types.VARCHAR(18),'score':types.NUMBER(6,2)}
    #return data.to_sql(ttb, con=db, dtype=dtyp, if_exists='append', index=False)
    #output = io.StringIO()
    #data.to_csv(output, sep='\t', index=False, header=False)
    #output.getvalue()
    #output.seek(0)
    db = create_engine(orcl_engien)  #不需要close()
    conn = db.raw_connection()
    #db = cx_Oracle.connect(orcl_engien[9:])
    cursor = conn.cursor()
    #cursor.copy_from(output, ttb, null='')
    col = ', '.join(data.columns.tolist())
    s = ', '.join([':'+str(i) for i in range(1, data.shape[1]+1)])
    sql = 'insert into {}({}) values({})'.format(ttb, col, s)
    #TypeError: expecting float,
    cursor.executemany(sql, data.values.tolist())
    conn.commit()
    cursor.close()
    #try:
    #except Exception as e:
    #    print(e)
    #finally:

　　定义重试装饰器

#定义一个重试修饰器，默认重试一次
def retry(num_retries=1, delay=2, random_sec_max=3):
    #用来接收函数
	import time
	import numpy as np
    def wrapper(func):
        #用来接收函数的参数
        def wrapper(*args,**kwargs):
            #为了方便看抛出什么错误定义一个错误变量
            #last_exception =None
            #循环执行包装的函数
            for _ in range(num_retries):
                try:
                    #如果没有错误就返回包装的函数，这样跳出循环
                    return func(*args, **kwargs)
                except Exception as err:
                    #捕捉到错误不要return，不然就不会循环了
                    #last_exception = e
					#np.random.randint(0,random_sec_max+1,size=10)
					time.sleep(delay + np.random.random()*random_sec_max)
					print(err)
			else:
				#如果要看抛出错误就可以抛出
				# raise last_exception
				raise 'ERROR: 超过retry指定执行次数！！'
				print('未执行参数为：', *args, **kwargs)
        return wrapper
    return wrapper