Python連線Oracle之環境配置、例項程式碼及報錯解決方法詳解
Oracle Client 安裝
1、環境
日期:2019年8月1日
公司已經安裝好Oracle服務端
Windows版本:Windows10專業版
系統型別:64位作業系統,基於x64的處理器
Python版本:Python 3.6.4 :: Anaconda,Inc.
2、下載網址
https://www.oracle.com/database/technologies/instant-client/downloads.html
3、解壓至目錄
解壓後(這裡放D盤)
4、配置環境變數
控制面板\系統和安全\系統 -> 高階系統設定 -> 環境變數
新建ORACLE_HOME,值為包解壓的路徑
編輯PATH,新增%ORACLE_HOME%
Navicat連線測試
cx_Oracle
安裝命令
conda install cx_Oracle
基礎程式碼
import cx_Oracle def execute(query): db = cx_Oracle.connect('使用者名稱/密碼@IP/ServiceName') cursor = db.cursor() cursor.execute(query) result = cursor.fetchall() cursor.close() db.close() return result def commit(sql): db = cx_Oracle.connect('使用者名稱/密碼@IP/ServiceName') cursor = db.cursor() cursor.execute(sql) db.commit() cursor.close() db.close()
封裝成類
from cx_Oracle import Connection # conda install cx_Oracle from conf import CONN,Color class Oracle(Color): def __init__(self,conn=CONN): self.db = Connection(*conn,encoding='utf8') # 使用者名稱 密碼 IP/ServiceName self.cursor = self.db.cursor() def __del__(self): self.cursor.close() self.db.close() def commit(self,sql): try: self.cursor.execute(sql) self.db.commit() except Exception as e: self.red(e) def fetchall(self,query): self.cursor.execute(query) return self.cursor.fetchall() def fetchone(self,query,n=9999999): self.cursor.execute(query) for _ in range(n): one = self.cursor.fetchone() if one: yield one def fetchone_dt(self,n=9999999): self.cursor.execute(query) columns = [i[0] for i in self.cursor.description] length = len(columns) for _ in range(n): one = self.cursor.fetchone() # tuple yield {columns[i]: one[i] for i in range(length)} def read_clob(self,query): self.cursor.execute(query) one = self.cursor.fetchone() while one: try: yield one[0].read() except Exception as e: self.red(e) one = self.cursor.fetchone() def db2sheet(self,prefix): df = pd.read_sql_query(query,self.db) if 'url' in df.columns: df['url'] = "'" + df['url'] df.to_excel(prefix.replace('.xlsx','')+'.xlsx',index=False) def db2sheets(self,queries,prefix): writer = pd.ExcelWriter(prefix.replace('.xlsx','')+'.xlsx') for sheet_name,query in queries.items(): df = pd.read_sql_query(query,self.db) if 'url' in df.columns: df['url'] = "'" + df['url'] df.to_excel(writer,sheet_name=sheet_name,index=False) writer.save() def tb2sheet(self,table): sql = "SELECT * FROM " + table self.db2sheet(sql,table) def insert(self,dt,tb): for k,v in dt.items(): if isinstance(v,str): dt[k] = v.replace("'",'').strip() ls = [(k,v) for k,v in dt.items() if v is not None] sql = 'INSERT INTO %s (' % tb + ','.join(i[0] for i in ls) + \ ') VALUES (' + ','.join('%r' % i[1] for i in ls) + ')' self.commit(sql) def insert_clob(self,tb,clob): for k,'').strip() # 把超長文字儲存在一個變數中 # declare = "DECLARE variate CLOB := '%s';\n" % dt[clob] join = lambda x: '||'.join("'%s'" % x[10922*i: 10922*(i+1)] for i in range(len(x)//10922+1)) # 32768//3 declare = "DECLARE variate CLOB := %s;\n" % join(dt[clob]) dt[clob] = 'variate' ls = [(k,'.join(i[0] for i in ls) + ') VALUES (' +\ ','.join('%r' % i[1] for i in ls) + ');' sql = declare + 'BEGIN\n%s\nEND;' % sql.replace("'variate'",'variate') self.commit(sql) def update(self,dt_update,dt_condition,table): sql = 'UPDATE %s SET ' % table + ','.join('%s=%r' % (k,v in dt_update.items()) \ + ' WHERE ' + ' AND '.join('%s=%r' % (k,v in dt_condition.items()) self.commit(sql) def truncate(self,tb): self.commit('truncate table ' + tb) db_read = Oracle() fetchall = db_read.fetchall fetchone = db_read.fetchone read_clob = db_read.read_clob if __name__ == '__main__': query = ''' '''.strip() for i in fetchone(query,99): print(i)
conf
CONN = ('使用者名稱','密碼','IP/ServiceName') conn = '使用者名稱/密碼@IP/ServiceName'
文字字串查詢
class INSTR(Oracle): """文字字串查詢""" def highlight_instr(self,table,field,keyword,clob=True): sql = "SELECT %s FROM %s WHERE INSTR(%s,'%s')>0" % (field,keyword) if clob: for i in self.read_clob(sql): self.highlight(i,keyword) else: for i,in self.fetchone(sql): self.highlight(i,keyword) def regexp_instr(self,pattern,regexp=True,pattern) sql = sql.replace('INSTR','REGEXP_INSTR') if regexp else sql if clob: for i in self.read_clob(sql): yield i else: for i,in self.fetchone(sql): yield i
一個簡單的建表示例
-- 建表 CREATE TABLE table_name ( serial_number NUMBER(10),collect_date DATE,url VARCHAR2(255),long_text CLOB,price NUMBER(10)-- 若需要精確到小數點2位,按分儲存,/100還原到元 ); -- 給表新增備註 COMMENT ON TABLE table_name IS '中文表名'; -- 給表字段新增備註 COMMENT ON COLUMN table_name.serial_number IS '編號'; COMMENT ON COLUMN table_name.collect_date IS '日期'; COMMENT ON COLUMN table_name.url IS 'URL'; COMMENT ON COLUMN table_name.long_text IS '長文字'; COMMENT ON COLUMN table_name.price IS '價錢'; -- 插入 INSERT INTO table_name(collect_date) VALUES (DATE'2019-08-23'); INSERT INTO table_name(long_text) VALUES ('a'); INSERT INTO table_name(long_text) VALUES ('b'); -- 查詢 SELECT * FROM table_name WHERE TO_CHAR(long_text) in ('a','b'); -- 查建表語句(表名大寫) SELECT dbms_metadata.get_ddl('TABLE','TABLE_NAME') FROM dual; -- 刪表 DROP TABLE table_name;
sqlalchemy
import os # 解決【UnicodeEncodeError: 'ascii' codec can't encode character】問題 os.environ['NLS_LANG'] = 'AMERICAN_AMERICA.AL32UTF8' # os.environ['NLS_LANG'] = 'SIMPLIFIED CHINESE_CHINA.UTF8' from cx_Oracle import makedsn from sqlalchemy import create_engine,Column,String,Integer from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.orm import sessionmaker # 連線資料庫(ORA-12505: TNS:listener does not currently know of SID given in connect descriptor) ip = '' port = '' tnsname = '' # 例項名 uname = '' # 使用者名稱 pwd = '' # 密碼 dsnStr = makedsn(ip,port,service_name=tnsname) connect_str = "oracle://%s:%s@%s" % (uname,pwd,dsnStr) # 建立連線引擎,這個engine是lazy模式,直到第一次被使用才真實建立 engine = create_engine(connect_str,encoding='utf-8') # 建立物件的基類 Base = declarative_base() class Student(Base): # 表名 __tablename__ = 'student' # 表字段 sid = Column(String(20),primary_key=True) age = Column(Integer) # 建表(繼承Base的所有表) Base.metadata.create_all(bind=engine) # 使用ORM操作資料庫 Session = sessionmaker(bind=engine) # 建立ORM基類 session = Session() # 建立ORM物件 tb_obj = Student(sid='a6',age=18) # 建立表物件 session.add(tb_obj) # 新增到ORM物件(插入資料) session.commit() # 提交 session.close() # 關閉ORM物件 # 刪表(繼承Base的所有表) Base.metadata.drop_all(engine)
報錯處理
DPI-1047: 64-bit Oracle Client library cannot be loaded
首先作業系統位數、python位數、cx_Oracle版本要對應上;另外可能缺【Visual C++】
每次裝完後,要重啟pycharm和python
ORA-12170: TNS:Connect timeout occurred
開啟終端ping一下
檢查【主機名或IP地址】、【服務名或SID】、【使用者名稱】和【密碼】是否填對
中文亂碼
encoding=‘utf8'
ORA-00972: identifier is too long
insert語句中出現'之類的字元
解決方法:將可能報錯的字元替換掉
ORA-64203: Destination buffer too small to hold CLOB data after character set conversion.
select TO_CHAR(long_text) from table_name,目標緩衝區太小,無法儲存CLOB轉換字元後的資料
解決方法:不在SQL用TO_CHAR,改在Python中用read(如上程式碼所示)
ORA-01704: string literal too long
雖然CLOB可以儲存長文字,但是SQL語句有長度限制
解決方法:把超長文字儲存在一個變數中(如上程式碼所示)
PLS-00172: string literal too long
字串長度>32767(215-1)
解決方法:使用'||'來連線字串(如上程式碼所示)
ORA-00928: missing SELECT keyword
INSERT操作時,表字段命名與資料庫內建名稱衝突,如:ID、LEVEL、DATE等
解決方法:建立命名規範
cx_Oracle.DatabaseError: ORA-12505: TNS:listener does not currently know of SID given in connect descriptor
使用sqlalchemy時的報錯
原因可能是目標資料庫是叢集部署的,可以諮詢一下DBA,或見上面程式碼from cx_Oracle import makedsn
UnicodeEncodeError: 'ascii' codec can't encode character
使用sqlalchemy時的報錯,插入中文字元引起
解決方法是設定os.environ['NLS_LANG']
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