Querying data in table likes you’re searching info in the book. And of course, it’s really worse if we have to read the whole book from the first page to the last page to find the info we want.
Index likes the book’s table of contents. Let’s say if you want to find an elephant, firstly you will open then contents-page to address what is the page number of elephant, then what you need is just open the book at exact this page number.
1. What is index ?
Index likes you pre-sort data into additional indexed-tables inform of key-value (with key is rowid). When…
set timing on
set serverout on size 1000000
set define off
set serveroutput on
set lines 9999
set pages 9999
set pagesize 9999
set linesize 9999
col refdoss format a15
column montant format 9999.999
alter session set NLS_DATE_FORMAT='yyyy/mm/dd hh24:mi:ss';spool on, spool offdesc tabledesc columns
Collection : components have the same data type, and are called elements.
Record : components can have the different data types, and are called fields.
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1.Lock rows by using SELECT..FOR UPDATE (OF)
- DML (Data Manipulation Language) : INSERT, UPDATE, DELETE, MERGE (it’ll exclusively lock rows, other people can’t see our changes and can’t modify these rows until we commit/rollback)
- SELECT is a sql, not a DML, so it won’t lock rows, in order to lock we can use “FOR UPDATE”
- To avoid session is waiting forever when rows are locked, we can use FOR UPDATE NOWAIT (SKIP LOCKED)
1.EXCEPTIONS, SQLCODE, ERRMSG, StackTrace, BackTrace
What is the difference between … and … ?
1. What is SQL, What are the types of SQL statements
- Caching
In case of we have a “popular” function, which is called many times during session. Then instead of querying database every time when this func is called, it’s better to cache them, then we can reuse later.
In this example, I created a map called “g_country_name” which is indexed by VARCHAR2(2). And we’ll cache it in the initialization block of “test.pck”
Map(Associative array) : the index is a string
i.e : g_country_name(‘UK’) = ‘United Kingdom’
Demo:
In the first time, when the session is get started and when test.getCountryName(‘US’) is called, it invoked the initialization of “test.pck” and…
In this article, I’ll show you how to crack C++ application whis is built into assembly.
To crack an app, you need to know its keyword i.e : “Unregistered”
Run “x32dbg” and open Bigasoft, goto “Symbols” tab, here we’ll see it’s at ntdll.dl. Double click to “videoconverter.exe”
ntdll.dll : is awindow’s dll. When we double click to run the app, it’ll call this dll to start the app
Here if we open dnSpy or CheatEngine, then MaxCare will be closed to prevent hack.
