How to clear data table data in mysql
In mysql, you can use the "DELETE" and "TRUNCATE" keywords to clear the data in the data table. The specific syntax is "DELETE FROM data table;" and "TRUNCATE TABLE data table;".
The operating environment of this tutorial: windows7 system, mysql8 version, Dell G3 computer.
MySQL provides the DELETE and TRUNCATE keywords to delete data in the table.
MySQL DELETE keyword
In MySQL, you can use the DELETE statement to delete one or more rows of data in a table.
Use the DELETE statement to delete data from a single table. The syntax format is:
DELETE FROM <表名> [WHERE 子句] [ORDER BY 子句] [LIMIT 子句]
The syntax description is as follows:
- ##
: Specify the table name from which data is to be deleted.
- ORDER BY clause: Optional. Indicates that when deleting, rows in the table will be deleted in the order specified in the clause.
- WHERE clause: Optional. Indicates that the deletion conditions are limited for the deletion operation. If this clause is omitted, it means that all rows in the table are deleted.
- LIMIT clause: Optional. Used to tell the server the maximum number of rows to be deleted before the control command is returned to the client.
Note: When the WHERE condition is not used, all data will be deleted.Delete all data in the table
Example: Delete all data in the tb_courses tablemysql> DELETE FROM tb_courses; Query OK, 3 rows affected (0.12 sec) mysql> SELECT * FROM tb_courses; Empty set (0.00 sec)
Copy after loginMySQL TRUNCATE keyword
The TRUNCATE keyword is used to completely clear a table. The syntax format is as follows:Among them, the TABLE keyword can be omitted. Example: Use the TRUNCATE statement to clear the records in the tb_student_course tableTRUNCATE [TABLE] 表名
Copy after login(Recommended tutorial:mysql> TRUNCATE TABLE tb_student_course; Query OK, 0 rows affected (0.04 sec) mysql> SELECT * FROM tb_student_course; Empty set (0.00 sec)
Copy after loginmysql video tutorial)
The difference between TRUNCATE and DELETE
Logically speaking, the TRUNCATE statement has the same effect as the DELETE statement, but in some cases, there are differences in their use.- DELETE is a DML type statement; TRUNCATE is a DDL type statement. They are both used to clear the data in the table.
- DELETE deletes records row by row; TRUNCATE directly deletes the original table and then creates an identical new table instead of deleting the data in the table row by row. Execute data faster than DELETE. Therefore, when you need to delete all data rows in the table, try to use the TRUNCATE statement to shorten the execution time.
- DELETE After deleting data, the data can be retrieved with event rollback; TRUNCATE does not support transaction rollback, and data cannot be retrieved after deletion.
- DELETE After deleting data, the system will not reset the counter of the auto-increment field; after TRUNCATE clears the table records, the system will reset the counter of the auto-increment field.
- DELETE has a wider scope of use because it can delete part of the data by specifying conditions through the WHERE clause; TRUNCATE does not support the WHERE clause and can only delete the entire data.
- DELETE will return the number of rows with deleted data, but TRUNCATE will only return 0, which is meaningless.
Introduction to Programming! !
The above is the detailed content of How to clear data table data in mysql. For more information, please follow other related articles on the PHP Chinese website!
Statement of this WebsiteThe 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
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)1 months ago By 尊渡假赌尊渡假赌尊渡假赌R.E.P.O. Best Graphic Settings1 months ago By 尊渡假赌尊渡假赌尊渡假赌Assassin's Creed Shadows: Seashell Riddle Solution2 weeks ago By DDDR.E.P.O. How to Fix Audio if You Can't Hear Anyone1 months ago By 尊渡假赌尊渡假赌尊渡假赌R.E.P.O. Chat Commands and How to Use Them1 months ago By 尊渡假赌尊渡假赌尊渡假赌
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
CakePHP Tutorial
1379
52
See all articles
MySQL: Simple Concepts for Easy Learning
Apr 10, 2025 am 09:29 AM
MySQL is an open source relational database management system. 1) Create database and tables: Use the CREATEDATABASE and CREATETABLE commands. 2) Basic operations: INSERT, UPDATE, DELETE and SELECT. 3) Advanced operations: JOIN, subquery and transaction processing. 4) Debugging skills: Check syntax, data type and permissions. 5) Optimization suggestions: Use indexes, avoid SELECT* and use transactions.
How to open phpmyadmin
Apr 10, 2025 pm 10:51 PM
You can open phpMyAdmin through the following steps: 1. Log in to the website control panel; 2. Find and click the phpMyAdmin icon; 3. Enter MySQL credentials; 4. Click "Login".
How to create navicat premium
Apr 09, 2025 am 07:09 AM
Create a database using Navicat Premium: Connect to the database server and enter the connection parameters. Right-click on the server and select Create Database. Enter the name of the new database and the specified character set and collation. Connect to the new database and create the table in the Object Browser. Right-click on the table and select Insert Data to insert the data.
MySQL: An Introduction to the World's Most Popular Database
Apr 12, 2025 am 12:18 AM
MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.
How to create a new connection to mysql in navicat
Apr 09, 2025 am 07:21 AM
You can create a new MySQL connection in Navicat by following the steps: Open the application and select New Connection (Ctrl N). Select "MySQL" as the connection type. Enter the hostname/IP address, port, username, and password. (Optional) Configure advanced options. Save the connection and enter the connection name.
Why Use MySQL? Benefits and Advantages
Apr 12, 2025 am 12:17 AM
MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.
How to use single threaded redis
Apr 10, 2025 pm 07:12 PM
Redis uses a single threaded architecture to provide high performance, simplicity, and consistency. It utilizes I/O multiplexing, event loops, non-blocking I/O, and shared memory to improve concurrency, but with limitations of concurrency limitations, single point of failure, and unsuitable for write-intensive workloads.
MySQL and SQL: Essential Skills for Developers
Apr 10, 2025 am 09:30 AM
MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.
