#Import librariesimport cx_Oracleimport mysql.connectorimport pandas as pdfrom sqlalchemy import create_engine#Set Oralce Connectionconn = cx_Oracle.connect('test/test@192.168.19.111/orcl')#Open cursorcursor =
例1:创建一个DML语句级触发器,当对emp表执行INSERT, UPDATE, DELETE 操作时,它自动更新dept_summary 表中的数据。由于在PL/SQL块中不能直接调用DDL语句,所以,利用ORACLE内置包DBMS_UTILITY中的EXEC_DDL_STATEMENT过程,由它执行DDL语句创建触发器。 CREATE TABLE dept_summary( Deptno NUMBER(2), Sal_sum NUMBER(...
问Oracle SQL在group by & select子句和CASE运算符中同时使用子查询EN下面来总计下之前的随笔中所说过...
CASE表达式:SQL99的语法,类似Basic,比较繁琐 DECODE函数:Oracle自己的语法,类似Java,比较简单 CASE表达式 CASE expr WHEN comparison_expr1 THEN return_expr1 [WHEN comparison_expr2 THEN return_expr2 WHEN comparison_exprn THEN return_exprn ELSE else_expr] END DECODE函数 DECODE(col|expression, search1, ...
Oracle数据库中的优化器是SQL分析和执行的优化工具,它负责制定SQL的执行计划,也就是它负责保证SQL执行效率最高.
语句级(STATEMENT)触发器:是指当某触发事件发生时,该触发器只执行一次; 行级(ROW)触发器:是指当某触发事件发生时,对受到该操作影响的每一行数据,触发器都单独执行一次。 编写触发器时,需要注意以下几点: l 触发器不接受参数。 l 一个表上最多可有12个触发器,但同一时间、同一事件、同一类型的触发器只能有一...
1数据库 /* mysql可以创建数据库,而oracle没有这个操作,oracle只能创建实例; sql数据库操作:database 格式: * create database 数据库名; * create database 数据库名 character set 字符集; */ CREATE DAT
SPACE SQL SQLCODE SQLERRM START STATEMENT STDDEV SUBTYPE SUM TABAUTH TABLE TABLES TASK TERMINATE THEN TO TRUE TYPE UNION UNIQUE UPDATE USE VALUES VARCHAR VARCHAR2 VARIANCE VIEW VIEWS WHEN WHERE WHILE WITH WORK XOR 及矢奈斥 棒及矢奈斥
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When a statement is executed on the logical standby database, it will access the database link at that time. It is not possible to know if the information on the logical standby database is the same as it was at the time the statement was executed on the primary database. For example...