mysql unique id

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

Original: Http://mp.weixin.qq.com/s/cqIK5Bv1U0mT97C7EOxmnA distributed unique ID minimalist tutorialOne, the signature All business systems have the need to generate IDs, such as order IDs, product IDs, article IDs, and so on. This ID will be the

This article mainly describes how to generate globally unique IDs in a distributed system. Preface Simply generating global IDs is not a challenge, generating a global unique ID to meet the following requirements: Ensure that the generated ID is

How PHP generates a unique numeric ID, note that it is numeric, do not string the Reply content: How PHP generates a unique numeric ID, note that it is numeric, do not string the Landlord, you are a big problem. Twitter,weibo and so on have

This article will introduce the differences between unique and primary constraints in mysql. unique and primary are the types we often use when creating mysql. Next I will introduce them to you. Fields defining the UNIQUE constraint cannot contain

Use LAST_INSERT_ID of MySQL to determine the unique ID value of each table Shard in the MySQL data table structure. generally, a 'id' field with the 'auto _ INCREMENT 'extension property is defined, to ensure that each record of the data table can

Http://www.cnblogs.com/lsx1993/p/4663125.html "Database primary key scheme in distributed environment" [Http://www.2cto.com/database/201309/243195.html] Using a self-added primary key ID is certainly the best fit when using only a single database.

MySQL tutorial How to use the unique index Grammar:UNIQUE KEY ' test ' (' Xref_key ', ' xref_dbname ')UNIQUE KEY ' Xref_key ' (' Xref_key ', ' xref_dbname ') The above syntax checks whether the combination of Xref_key and Xref_dbname is a unique

PHP generated unique numeric id method summary, PHP generation ID Summary Regarding the question of generating a unique numeric ID, is it necessary to use Rand to generate a random number and then go to the database query for this number? It's a

In mysql, key, primary key, unique key and index are different, mysqlunique Indexes in mysql are very important knowledge points. Compared with other knowledge points, indexes are more difficult to master, and there are many index types in mysql,