In MySQL, the REPLACE() function can replace the string in the field. The syntax is UPDATE table name. SET field name = REPLACE(field name, 'old content', 'new content'); 1. This operation is replaced globally and case-sensitive; 2. It is recommended to perform backup or add WHERE conditional tests; 3. The replacement effect can be previewed in SELECT; 4. Pay attention to avoiding error substitution, performance impact and data backup problems.
In MySQL, if you want to search for strings in a field and replace some content, the most common method is to use the REPLACE() function. This function can help you quickly update the values ??of certain fields in the table, such as fixing error data, unified format, etc.
How to use the REPLACE() function
MySQL's REPLACE(str, from_str, to_str) function replaces all from_str in the string str to_str . It's very straightforward and the syntax is simple:
UPDATE table name SET Field name = REPLACE(field name, 'the content to be replaced', 'the content to be replaced');
For example, suppose you have an article table articles with a content field inside. You want to replace the " http://m.miracleart.cn/link/658900b7144ee7b4f419cb8054361045 " in all articles with " http://m.miracleart.cn/link/80b912d8d81919969ccab0080ddd8e2f :
UPDATE articles SET content = REPLACE(content, 'http://m.miracleart.cn/link/658900b7144ee7b4f419cb8054361045', 'https://example.com');
What should be noted is:
- This operation is a global replacement , which means that all matching parts in the field will be replaced
- It is case-sensitive (unless your fields are case-insensitive sorting rules)
- Once executed, the data will be modified. It is recommended to back up or add
WHEREconditions to test it.
Do search and replace when querying without modifying the original data
If you just want to see the replacement in the query result and don't really want to change the content in the database, you can also use REPLACE() in the SELECT statement:
SELECT id, REPLACE(content, 'old content', 'new content') AS new_content FROM articles;
In this way, you can preview the replacement effect and confirm that there is no problem before deciding whether to execute UPDATE .
Notes and FAQs
Don't forget to add WHERE condition : If you only want to replace specific records, remember to add the
WHEREclause, otherwise the data of the entire table will be updated.UPDATE articles SET content = REPLACE(content, 'old-text', 'new-text') WHERE id = 100;
Avoid misreplacement : If the replaced content appears where you do not want it, such as "old-text" appears in the middle of other words, it may also be replaced. This situation may require more complex logic, such as incorporating regular expressions (MySQL 8.0 supports
REGEXP_REPLACE()).Performance Impact : Performing full-field replacement for large tables may be slower, especially fields without indexes. It is recommended to operate during the low peak period or process in batches.
Backup is very important : it is best to export relevant data before execution to prevent data loss due to replacement errors.
Basically that's it. Mastering REPLACE() and REGEXP_REPLACE() will be much more convenient for daily maintenance or data cleaning.
The above is the detailed content of mysql find and replace in string. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
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
What is GTID (Global Transaction Identifier) and what are its advantages?
Jun 19, 2025 am 01:03 AM
GTID (Global Transaction Identifier) ??solves the complexity of replication and failover in MySQL databases by assigning a unique identity to each transaction. 1. It simplifies replication management, automatically handles log files and locations, allowing slave servers to request transactions based on the last executed GTID. 2. Ensure consistency across servers, ensure that each transaction is applied only once on each server, and avoid data inconsistency. 3. Improve troubleshooting efficiency. GTID includes server UUID and serial number, which is convenient for tracking transaction flow and accurately locate problems. These three core advantages make MySQL replication more robust and easy to manage, significantly improving system reliability and data integrity.
What is a typical process for MySQL master failover?
Jun 19, 2025 am 01:06 AM
MySQL main library failover mainly includes four steps. 1. Fault detection: Regularly check the main library process, connection status and simple query to determine whether it is downtime, set up a retry mechanism to avoid misjudgment, and can use tools such as MHA, Orchestrator or Keepalived to assist in detection; 2. Select the new main library: select the most suitable slave library to replace it according to the data synchronization progress (Seconds_Behind_Master), binlog data integrity, network delay and load conditions, and perform data compensation or manual intervention if necessary; 3. Switch topology: Point other slave libraries to the new master library, execute RESETMASTER or enable GTID, update the VIP, DNS or proxy configuration to
How to connect to a MySQL database using the command line?
Jun 19, 2025 am 01:05 AM
The steps to connect to the MySQL database are as follows: 1. Use the basic command format mysql-u username-p-h host address to connect, enter the username and password to log in; 2. If you need to directly enter the specified database, you can add the database name after the command, such as mysql-uroot-pmyproject; 3. If the port is not the default 3306, you need to add the -P parameter to specify the port number, such as mysql-uroot-p-h192.168.1.100-P3307; In addition, if you encounter a password error, you can re-enter it. If the connection fails, check the network, firewall or permission settings. If the client is missing, you can install mysql-client on Linux through the package manager. Master these commands
Why do indexes improve MySQL query speed?
Jun 19, 2025 am 01:05 AM
IndexesinMySQLimprovequeryspeedbyenablingfasterdataretrieval.1.Theyreducedatascanned,allowingMySQLtoquicklylocaterelevantrowsinWHEREorORDERBYclauses,especiallyimportantforlargeorfrequentlyqueriedtables.2.Theyspeedupjoinsandsorting,makingJOINoperation
Why is InnoDB the recommended storage engine now?
Jun 17, 2025 am 09:18 AM
InnoDB is MySQL's default storage engine because it outperforms other engines such as MyISAM in terms of reliability, concurrency performance and crash recovery. 1. It supports transaction processing, follows ACID principles, ensures data integrity, and is suitable for key data scenarios such as financial records or user accounts; 2. It adopts row-level locks instead of table-level locks to improve performance and throughput in high concurrent write environments; 3. It has a crash recovery mechanism and automatic repair function, and supports foreign key constraints to ensure data consistency and reference integrity, and prevent isolated records and data inconsistencies.
What are the transaction isolation levels in MySQL, and which is the default?
Jun 23, 2025 pm 03:05 PM
MySQL's default transaction isolation level is RepeatableRead, which prevents dirty reads and non-repeatable reads through MVCC and gap locks, and avoids phantom reading in most cases; other major levels include read uncommitted (ReadUncommitted), allowing dirty reads but the fastest performance, 1. Read Committed (ReadCommitted) ensures that the submitted data is read but may encounter non-repeatable reads and phantom readings, 2. RepeatableRead default level ensures that multiple reads within the transaction are consistent, 3. Serialization (Serializable) the highest level, prevents other transactions from modifying data through locks, ensuring data integrity but sacrificing performance;
What are the ACID properties of a MySQL transaction?
Jun 20, 2025 am 01:06 AM
MySQL transactions follow ACID characteristics to ensure the reliability and consistency of database transactions. First, atomicity ensures that transactions are executed as an indivisible whole, either all succeed or all fail to roll back. For example, withdrawals and deposits must be completed or not occur at the same time in the transfer operation; second, consistency ensures that transactions transition the database from one valid state to another, and maintains the correct data logic through mechanisms such as constraints and triggers; third, isolation controls the visibility of multiple transactions when concurrent execution, prevents dirty reading, non-repeatable reading and fantasy reading. MySQL supports ReadUncommitted and ReadCommi.
How to add the MySQL bin directory to the system PATH
Jul 01, 2025 am 01:39 AM
To add MySQL's bin directory to the system PATH, it needs to be configured according to the different operating systems. 1. Windows system: Find the bin folder in the MySQL installation directory (the default path is usually C:\ProgramFiles\MySQL\MySQLServerX.X\bin), right-click "This Computer" → "Properties" → "Advanced System Settings" → "Environment Variables", select Path in "System Variables" and edit it, add the MySQLbin path, save it and restart the command prompt and enter mysql--version verification; 2.macOS and Linux systems: Bash users edit ~/.bashrc or ~/.bash_
