在第一章从CSV中获取数据后，需要将提取的数据或经Pandas等处理后的数据进行存储。这里简单介绍下使用cx-Oracle操作数据库，和通过Oracle的数据载入工具sqlldr来匹配导入数据。

1.cx-Oracle

1.1.安装：

pip install cx_Oracle

1.2.安装oracle客户端，并添加到Path

oracle客户端下载地址
(安装过程，及Linux环境变量过程，略)

1.3.示例代码

操作Oracle工具 oracle_utils.py

class ConnectOracleDatabase(object):

    def __init__(self):
        self.user = DB_USER
        self.password = DB_PASSWORD
        self.ip = DB_IP
        self.port = DB_PORT
        self.service_name = DB_SERVICE
        self.oci_path = ORACLE_OCI_DIR

        # 这种设置环境变量，在Pycharm中运行无效
        # 在菜单Run->Edit configurations 中，手动设置Environment variables，添加LD_LIBRARY_PATH的内容，即可解决问题。
        # LD_LIBRARY_PATH=/home/oracle/instantclient_19_5
        sys_version = platform.architecture()
        if sys_version[1] is not 'WindowsPE':
            os.environ['LD_LIBRARY_PATH'] = self.oci_path
        else:
            os.environ['PATH'] = os.environ['PATH'] + ';' + self.oci_path

        # 解决中文乱码问题
        os.environ['NLS_LANG'] = 'SIMPLIFIED CHINESE_CHINA.ZHS16GBK'

        self.db_conn = None
        self.db_cursor = None

        self.create_connect()

    def create_connect(self):
        try:
            self.db_conn = cx_Oracle.connect(self.user, self.password,
                                             '%s:%s/%s' % (self.ip,
                                                           self.port,
                                                           self.service_name))
            self.db_cursor = self.db_conn.cursor()
        except Exception as error:
            print("Error creating database connection: %s" % str(error))

     # 执行DDL语句
    def exec_sql_command(self, sql_command):
        if sql_command:
            print('ddl sql is', sql_command)
            query_result = self.db_cursor.execute(sql_command)
            return query_result 

    # 返回SQL的所有值
    def query_sql(self, sql):
        self.db_cursor.execute(sql)
        return self.db_cursor.fetchall()

    def __enter__(self):
        self.create_connect()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        try:
            self.db_cursor.close()
            self.db_conn.close()
        except AttributeError as error:
            print(str(error))

使用示例：

        with ConnectOracleDatabase() as oracle:
                    oracle.exec_sql_command('create table person(id number(10),name varchar2(255))')

2.Python执行sqlldr入库

cx-Oracle可以处理少量数据，一旦数据量过大则效率就会降低。所以较大的结果数据入库一般使用数据库自身提供的工具，这里以sqlldr举例：

2.1.示例代码

主要分两部分，一是根据数据模型，生成sqlldr的控制文件。二是由Python直接调用sqlldr。

生成sqlldr控制文件ctl

    # 在环境变量ORACLE_CTL_PATH指定的目录中生成ctl文件
    ctl_path = os.path.join(os.environ[ORACLE_CTL_PATH], table_name+'.ctl')
    if not os.path.exists(ctl_path):
        with open(ctl_path, 'w', encoding='utf-8') as file:
            file.write("load data"+os.linesep)
            file.write("replace into table " + table_name + os.linesep)
            file.write("fields terminated by '" + terminated + "'" + os.linesep)
            file.write("trailing nullcols (" + os.linesep)
            table_conf = zip(table_fields, table_fields_type)
            colunms_tmps=[]
            for fields, fields_type in table_conf:
                colunms_tmp = fields
                if 'NUMBER' in fields_type.upper():
                    colunms_tmp = colunms_tmp + ' DECIMAL EXTERNAL'
                elif 'DATE' in fields_type.upper():
                    colunms_tmp = colunms_tmp + ' date "yyyy-mm-dd hh24:mi:ss"'
                colunms_tmps.append(colunms_tmp)
            file.write(','.join(colunms_tmps)+' TERMINATED BY WHITESPACE )' + os.linesep)

调用sqlldr数据入库

    # 判断文件编码 ,直接结局sqlldr导入中文乱码问题
    with open(data, 'rb') as f:
        filedata = f.read()
        print('file infos is', chardet.detect(filedata))
        if 'GB' in chardet.detect(filedata)['encoding']:
            os.environ['NLS_LANG'] = 'SIMPLIFIED CHINESE_CHINA.ZHS16GBK'
        else:
            os.environ['NLS_LANG'] = 'AMERICAN_AMERICA.AL32UTF8'

    # 导入数据
    sqllod_command = os.environ['ORACLE_HOME']+'/sqlldr userid='+DB_USER+'/'+DB_PASSWORD+TNSNAME
    sqllod_command += ' control=' + ctl_path
    sqllod_command += ' data=' + data
    sqllod_command += ' log=' + os.path.join(os.environ[ORACLE_LOG_PATH], table_name+'.log')
    sqllod_command += ' skip_index_maintenance=true readsize=15000000 streamsize=15000000 ' \
                      'columnarrayrows=5000 rows=1000 errors=1000000 direct=true skip=1'
    print('sqllod_command=', sqllod_command)
    print(os.environ['NLS_LANG'])
    os.system(sqllod_command)

Python数据分析-第2章抽取数据到Oracle