Use float data type with caution in database (reprint)

Tags: Use the float data type with caution in the database   most programming languages support a float or double data type. There are also data types for the same keywords in the database, so many developers naturally use float as a field

SQL injection principle explanation, very good!

Label:Original address: abstractRecently, the country's largest program ape Community CSDN site user database was hacked public, 6 million users of the login name and password was

Listener.ora, Sqlnet.ora, Tnsnames.ora relationships and manual configuration

Label:Listener.ora, Sqlnet.ora, Tnsnames.ora, are placed in the $oracle_home\network\admin directory.    --begin Focus: The role and use of three files    #-----------------------Sqlnet.ora (client and server side)-a nsswitch.conf file that acts

SQL optimization----million data query optimization

Label:Millions of data query optimization1. Fair use IndexAn index is an important data structure in a database, and its fundamental purpose is to improve query efficiency. Most database products now use the ISAM index structure first proposed by

windbg symbol and source code "second article"

Label:A symbol file is a secondary data that contains some annotation information about the application code that is useful during debugging. If there is no secondary data, then the information available is only the binary file of the application.

Case in SQL and then else end usage

Label:--Simple case function when ' 1 ' then ' Male ' when ' 2 ' then ' women ' else ' other ' end--case search function case when sex = ' 1 ' Then ' man ' when Sex = ' 2 ' Then ' women ' else ' other ' ENDIn both of these

SQL Row to Column rollup

Label:SQL Row to Column rollupPivot is used to rotate column values to column names (row to column), and SQL Server 2000 can be implemented with an aggregate function with a case statementThe general syntax for pivot is: Pivot (aggregate function

SQL transaction (Transaction) usage introduction and rollback instance

Label:A transaction executes a sequence of operations as a unit, either succeeds or fails, and rolls back to its original state. In transactional terminology, a transaction is either committed or aborted. To commit a transaction, all participants


Label:Causes SQL Server to follow the ISO rules for quotation-delimited identifiers and literal strings. identifiers delimited by double quotation marks can be Transact-SQL reserved keywords, or they can contain characters that are normally

Command-line tools on your Mac

Label:Turn to self-love rice Home Blog, original: "Eight Terminal Utilities every OS X Command line User should Know"OS X's Terminal terminal opens up the world of powerful UNIX utilities and scripts. If you are a user who has been transferred from

Ubuntu modify file or directory permissions

Tags: Ubuntu permissions1. query file (or directory) permissionsQuerying file permissions, using the command: Ls-l file nameQuery folder permissions, using the command: LS-LD directory nameFor example:The first character specifies the file type (if

Handler must be instantiated in the main thread? The difference between New Handler () and New Handler (Looper.getmainlooper ())

Label:The collation of a post:Handler must be instantiated in the main thread? The difference between New Handler () and New Handler (Looper.getmainlooper ())If you instantiate without parameters: Handler Handler = new Handler (), then this will

The application of consistent hash algorithm in memcached

Label:ObjectiveEveryone should know that memcached to achieve distributed only in the client to complete, the current is more popular through the consistent hash algorithm to achieve. The general approach is to balance the hash value of the server

Questions about string Sort merging

Label:Today, a problem was encountered, the main idea is to enter two strings, and then give the two strings according to the ASCII code from small to large to sort, and finally in the merging of two strings, requires the deletion of the same

Use array helper functions to implement unlimited order filling parameters

Label:In general, we often need to pass arguments to a function when we define a function in a class1<?PHP2 3 classimage{4 5 Private $name;6 Private $age;7 Private $adress;8 9

Fourth Chapter Language Module

Label:1. Extension and repair of stringsLanguage scripts are particularly concerned with strings, and there are three main types of methods:First Class: Tag-independent implementations :

Lua Common API

Label:Transferred from: Build a new tablevoid Lua_createtable (lua_state *l, int narr, int nrec)Create a new table and put it on top of the stack. Narr and Nrec Specify the number of

Qt gui@ Learning Log

Label:Day 1:QT class:It is best to understand a class from its Class code implementation.This diagram shows that there are several important classes that need to be studied: qt/qevent/qobject/qwidget/.Qapplication: (more complex and very common)

Acdream 1195 Sudoku Checker (violence)

Label:Sudoku CheckerTime Limit:2000/1000MS (Java/others)Memory Limit:128000/64000KB (Java/others)Submitstatusproblem DescriptionSudoku is a popular single player game. The objective is to fill a 9x9 matrix with digits so, each column, each row, and

Leetcode172:factorial Trailing Zeroes

Label:anintegerreturnthenumberofinintime complexity.This problem requires solving the number of end 0 in the factorial in logarithmic time.The number of factorial in 0 is determined by the number of factors 2 and 5, and because factorial is the

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