How Can I Remove Duplicate Rows in MySQL Based on SID?

Removing Duplicate Rows Based on SID Using MySQL

You wish to eliminate duplicate rows identified by a specific SID in a MySQL table. An SQL query can be utilized to achieve this task.

SQL Query:

The following SQL query can be used to delete duplicate rows:

ALTER IGNORE TABLE `table_name` ADD UNIQUE (title, SID)

Explanation:

• ALTER IGNORE TABLE: Modifies the specified table without raising errors if duplicate keys are encountered.
• table_name: The name of the table you want to modify.
• ADD UNIQUE: Creates a unique index on the title and SID columns.

How it Works:

• This query creates a unique index on the specified columns.
• When data is inserted into the table, the database engine checks the index to ensure that no duplicate rows exist.
• Any duplicate rows that are encountered are ignored.

Note:

The effectiveness of this approach depends on the size of the index and whether it can fit in memory. If the index is too large, the query performance may be impacted.

The above is the detailed content of How Can I Remove Duplicate Rows in MySQL Based on SID?. For more information, please follow other related articles on the PHP Chinese website!