2fa key

The Keytool is an effective security key and certificate management tool. The Keytool.exe (located in the Jdk\bin directory) in Java can be used to create a digital certificate, and all digital certificates are stored in a certificate library in a single article (distinguished by Alias), and a certificate in the certificate store contains the private key of the certificate. The public

http://www.shangxueba.com/jingyan/122163.html primary key:1. PRIMARY KEY constraint: A table can have only one primary KEY constraint. The primary key can be a single field, or it can be multiple fields. In either case, all of its fields are not NULL.2.Unique constraints: A table can have multiple unique constraints, a

Primary key: Primary key A table has a single primary key, and the key value can be unique. You can set the primary key to self-increment.Foreign key: Represents the related relationship between two relationships. A table with a f

Original link: http://www.cppblog.com/wolf/archive/2014/05/09/69089.htmlAfter MySQL version 3.23.44, the InnoDB Engine type table supports foreign KEY constraints. Use conditions for foreign keys:1. Two tables must be a InnoDB table, the MyISAM table temporarily does not support foreign keys (it is said that later versions may be supported, but at least not currently supported);2. The foreign key column mus

The RSA algorithm is the first algorithm that can be used for both encryption and digital signature, and it is easy to understand and manipulate. RSA is the most widely researched public-key algorithm, from the proposed to now nearly 20 years, experienced a variety of attacks, gradually accepted by people, generally considered to be one of the best public key scheme at present. RSA's security relies on the

1 differences between a primary key and a foreign key1.1 DefinitionsPrimary Key-uniquely identifies a record, cannot be duplicated, is not allowed to be emptyForeign key--the foreign key of the table is the primary key of another table, the foreign

How does MySQL process the unique primary key duplicate value during the insertion process? mysql primary keyIntroduction This article describes how to avoid DUPLICATE keys when inserting data into a table. It mainly involves IGNORE, on duplicate key update, and REPLACE; next, let's take a look at the three solutions. IGNORE Ignore is used to automatically ignore duplicate record rows when the inserted val

Tags: Oracle PRIMARY key PRIMARY KEY PK PRIMARY KEY constraint databaseOracle/plsql: Primary KEY (Primary key) usage1 GoalsExamples explain how to create, delete, disable, and turn on primary keys.2 Preface-What is the primary keyIn Oracle, a primary

Do you know the key points of the car rental system ?, Key points of the vehicle rental system Vehicle rental system The main interface is as follows: Key Aspect 1: How to clarify the relationships between classes? Four classes are required: Car class, Truck class, Vehicle class, And VehicleUtil class. Car: small cars mainly include the calculation method of Ca

For example, the commodity table and the attribute table, because it is many-to-many relationship, so there is a commodity attribute intermediate table; CREATE TABLE IF not EXISTS dslxs_goods_attr( goods_idMediumint (8) unsigned not NULL COMMENT ' Product ID ', attr_idMediumint (8) unsigned not NULL COMMENT ' property id ', KEY goods_id( goods_id), KEY attr_id( attr_id) Engine=innodb DEFAULT Charset=utf8

Rimary key database PRIMARY KEY constraint Database PRIMARY KEY constraintThe PRIMARY KEY constraint uniquely identifies each record in a database table. The primary key must contain unique values. Primary key columns cannot co

Tags: allow span to add strict nod keep data repeating mysq data1, definition: If one table has one field pointing to the primary key of another table, the primary key field in the child table is called the foreign key.　　　Multiple foreign keys can exist in a single table2, the role of foreign keys　　Maintain consistency and integrity of dataA, the role of the chil

Label:Primary key a database primary key is a combination of one column or column in a table whose value uniquely identifies each row in the table. Such a column or columns is called the table's primary key, which enforces the entity integrity of the table. When you create or change a table, you can Create a primary key