You can create an index on an existing MariaDB table by using the ALTER TABLE statement, followed by ADD INDEX:
To create an index on a single column:
```
ALTER TABLE table_name ADD INDEX index_name (column_name);
```
To create an index on multiple columns:
```
ALTER TABLE table_name ADD INDEX index_name (column1, column2, …);
```
In the above SQL statements:
- `table_name` is the name of your table.
- `index_name` is the name you choose for the index.
- `column_name`, `column1`, `column2`… are the names of the columns in the table that you want to create the index on.
Here’s an example:
```
ALTER TABLE customers ADD INDEX idx_lastname (lastname);
```
This SQL statement adds an index named “idx\_lastname” to the “customers” table on the “lastname” column.
