Key differs from primary keyKey is usually the index synonym. If the keyword attribute primary key is given in the column definition, then primary key can also be specified as key only. The purpose of this is to be compatible with other database
BrieflyThe Qtemporaryfile class is an I/O device that operates temporary files.Qtemporaryfile is used to securely create a unique temporary file. The temporary file is created by calling Open (), and the name is unique (that is, guaranteed not to
------------I do not have him, but the hand is ripe, humble and foolish, and eager to be hungry-------------This blog has to say, how to create a unique file name , create a unique string string Why create a unique ? In many cases, such as file
Index type1. Unique index: Unique index does not allow two rows to have the same index value2. Primary KEY index: Defining a primary key for a table will automatically create a primary key index, which is a special type of unique index. The primary
GUID, the abbreviation of "Global Unique Identifier", is a unique reference number used as an Identifier in computer softw Is.GUIDs is usually stored as 128-bit values, and is commonly displayed as + hexadecimal digits with groups separated by H
String tempnam (string $ Dir, string $ prefix)Create a file with a unique file name in the specified directory. If the directory does not exist, tempnam () generates a file in the temporary directory of the system and returns the file name.
Before
You may have noticed the fact that because a package never really "encapsulates" into a single file, it can be composed of multiple. class files, so the situation may be slightly confusing. The most reasonable way to avoid this problem is to place
You can use the machine (computer) unique code + upload IP + current timestamp + GUID (+ random number), and then MD5 as the file name. The machine's unique code has the CPU information of the computer and the MAC address, both of which need to be
(Original link: http://blog.csdn.net/carefree31441/article/details/3998553)The UUID meaning is a universal unique identifier (universally unique Identifier), which is a software construction standard and is also organized by the Open Software
Use the PHPuniqid function to generate a unique ID. The PHPuniqid function is used to generate a unique ID. it is common to use phpuniqid to generate a unique id, such as the temporary cache file name, temporary variables, temporary security code,
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