Is the MySQL query using an index?

To check if an index is used, you can use the EXPLAIN keyword in MySQL to analyze the query execution plan. The EXPLAIN keyword displays the execution plan of the query, including whether an index is used, the type of index used, and the reading order of the table. The steps to check if an index is used using the EXPLAIN keyword are as follows: 1. Open the MySQL command line or graphical interface and connect to the database. 2. Use the EXPLAIN keyword to analyze the execution plan of the query statement. The syntax is as follows:

   EXPLAIN SELECT * FROM table_name WHERE condition;

In the query statement, the table_name is the name of the table to be queried, and the condition is the query condition. When executing the above query statement, MySQL will return a result set that contains the execution plan information of the query. Important fields in the execution plan include: type, which represents the access type (common types include ALL for full table scan, index for index scan, range for index range scan, etc.), key, which indicates the index used, key_len, which represents the length of the index fields, ref, which indicates the reference between the index and the table, and rows, which represents the number of rows scanned. Based on the information in the execution plan, you can determine whether an index is being used. If the type is index, it means an index is being used; if the type is ALL, it means no index is being used. By following these steps, you can query and determine whether MySQL queries are using an index.