How to create an index in MySQL to improve query performance.

In MySQL, you can use the CREATE INDEX statement to create an index to improve query performance. Here is an example:

CREATE INDEX idx_lastname ON customers(last_name);

This will create an index named “idx_lastname” on the “last_name” column in a table named “customers”. After creating the index, querying this column will be faster because MySQL will use the index to quickly locate the desired data. When creating an index, it is recommended to consider columns that are frequently used in queries and avoid creating indexes on unnecessary columns as this will increase the database’s space usage.