国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Home Common Problem Characteristics of relational databases

Characteristics of relational databases

Apr 19, 2024 am 10:48 AM
Sensitive data

Features of relational databases include: table structuring; relationship establishment; data integrity constraints (primary key, foreign key, non-null); transaction support; data manipulation language (DML); data query language (DQL); and data security measures.

Characteristics of relational databases

Characteristics of relational database

Relational database is a database that organizes and stores data in the form of data tables management system. It has the following main features:

1. Table structure:
Data in a relational database is stored in a relational structure called a table. A table consists of rows and columns, where rows represent individuals of entities and columns represent attributes of those entities.

2. Relationship:
The relationship between tables is established through foreign keys. A foreign key is a column or set of columns that references a primary key in another table, indicating a relationship between the two tables. This allows connections to be made between different tables.

3. Data integrity:
Relational databases ensure data integrity through constraints, which specify the rules that the data must follow. Common constraints include:

  • Primary key constraints: Ensure that a row in each table is identified by a unique identifier (primary key).
  • Foreign key constraints: Ensure that the foreign key column refers to rows that exist in the main table.
  • Non-null constraint: Ensure that null values ??are not allowed in the column.

4. Transaction support:
Relational databases ensure data consistency through transaction support. A transaction is a sequence of operations that either all succeed or all fail. This prevents incomplete or inconsistent data updates.

5. Data Manipulation Language (DML):
Relational databases use DML (such as SQL) to perform data manipulation operations. DML commands allow users to create tables, insert, update, and delete data.

6. Data Query Language (DQL):
Relational databases use DQL (such as SQL) to retrieve data. DQL commands allow users to query data using advanced conditions and produce the desired results.

7. Data security:
Relational database supports data security measures, such as:

  • Access control: restrict user access to data.
  • Authentication: Verify user identity.
  • Encryption: Protect sensitive data from unauthorized access.

The above is the detailed content of Characteristics of relational databases. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

The difference between oracle database and mysql The difference between oracle database and mysql May 10, 2024 am 01:54 AM

Oracle database and MySQL are both databases based on the relational model, but Oracle is superior in terms of compatibility, scalability, data types and security; while MySQL focuses on speed and flexibility and is more suitable for small to medium-sized data sets. . ① Oracle provides a wide range of data types, ② provides advanced security features, ③ is suitable for enterprise-level applications; ① MySQL supports NoSQL data types, ② has fewer security measures, and ③ is suitable for small to medium-sized applications.

What is the value and use of icp coins? What is the value and use of icp coins? May 09, 2024 am 10:47 AM

As the native token of the Internet Computer (IC) protocol, ICP Coin provides a unique set of values ??and uses, including storing value, network governance, data storage and computing, and incentivizing node operations. ICP Coin is considered a promising cryptocurrency, with its credibility and value growing with the adoption of the IC protocol. In addition, ICP coins play an important role in the governance of the IC protocol. Coin holders can participate in voting and proposal submission, affecting the development of the protocol.

The difference between get and post in vue The difference between get and post in vue May 09, 2024 pm 03:39 PM

In Vue.js, the main difference between GET and POST is: GET is used to retrieve data, while POST is used to create or update data. The data for a GET request is contained in the query string, while the data for a POST request is contained in the request body. GET requests are less secure because the data is visible in the URL, while POST requests are more secure.

How to convert XML files to PDF on your phone? How to convert XML files to PDF on your phone? Apr 02, 2025 pm 10:12 PM

It is impossible to complete XML to PDF conversion directly on your phone with a single application. It is necessary to use cloud services, which can be achieved through two steps: 1. Convert XML to PDF in the cloud, 2. Access or download the converted PDF file on the mobile phone.

How to delete a repository by git How to delete a repository by git Apr 17, 2025 pm 04:03 PM

To delete a Git repository, follow these steps: Confirm the repository you want to delete. Local deletion of repository: Use the rm -rf command to delete its folder. Remotely delete a warehouse: Navigate to the warehouse settings, find the "Delete Warehouse" option, and confirm the operation.

Recommended XML formatting tool Recommended XML formatting tool Apr 02, 2025 pm 09:03 PM

XML formatting tools can type code according to rules to improve readability and understanding. When selecting a tool, pay attention to customization capabilities, handling of special circumstances, performance and ease of use. Commonly used tool types include online tools, IDE plug-ins, and command-line tools.

How to verify social security number string in PHP? How to verify social security number string in PHP? May 23, 2025 pm 08:21 PM

Social security number verification is implemented in PHP through regular expressions and simple logic. 1) Use regular expressions to clean the input and remove non-numeric characters. 2) Check whether the string length is 18 bits. 3) Calculate and verify the check bit to ensure that it matches the last bit of the input.

Is Coinone a formal trading platform? Is Coinone a formal trading platform? Aug 21, 2024 pm 03:24 PM

Coinone is a formal cryptocurrency trading platform founded in 2014 and is one of the leading trading platforms in South Korea. It is known for its transparency, security, reliability, and wide selection of digital assets. Coinone complies with Korean government regulations and provides transparent fees and clear transaction information. It uses industry-leading security measures, including 2FA, cold storage, and DDoS protection. Coinone has strong liquidity, ensures fast transactions, and provides over-the-counter trading and a user-friendly interface. But it is mainly targeted at the Korean market and transaction fees may be slightly higher.