摘要： 1. Describe Signals & Slots.A: Signals ans Slots are used for communication between objects. It shall replace generally way of callbacks to avoid the flaws from callbacks. Any class deprived from QObject can have its own signals and slots.2. How Signals & Slots work? What is MetaObject syste 阅读全文

摘要： static关键字是C,C++中都存在的关键字,它主要有三种使用方式,其中前两种只指在C语言中使用, 第三种在C++中使用(C,C++中具体细微操作不尽相同,本文以C++为准).(1)局部静态变量(2)外部静态变量/函数(3)静态数据成员/成员函数下面就这三种使用方式及注意事项分别说明一、局部静态变量在C/C++中,局部变量按照存储形式可分为三种auto,static,register(<C语言程序设计(第二版)>谭浩强,第174-175页)与auto类型(普通)局部变量相比,static局部变量有三点不同1.存储空间分配不同auto类型分配在栈上,属于动态存储类别,占动态存储区空 阅读全文

摘要： List tables and their corresponding tablespace name and data fileFollowing is a way to list a table name and its corresponding tablespace name and data file.SQL>select t.table_name,t.tablespace_name,df.file_name from dba_tables t, dba_data_files df2 where t.tablespace_name = df.tablespace_name;Fu 阅读全文

摘要： If you need to remove duplicate rows from an Oracle Database Table, you can use different approaches. For example, you can use the DELETE command with a criteria that selects only duplicates. Usually it is faster to create a new table with distinct rows and replace the old table with the new one.-- 阅读全文

摘要： This example illustrates how you can create and use dynamic cursor in Oracle PL/SQL. The example is pretty simple, but I hope you can get the idea and apply it to more complicated cases.DECLARE t_cursor IS REF CURSOR; my_cursor t_cursor; v_customer RECORD ( customer_id NUMBER(18), amount NUM... 阅读全文