You can use the CREATE INDEX statement to create an index in Oracle. Here's the basic syntax,
CREATE INDEX index_name
ON table_name (column1, column2, ...);
In this syntax, index_name is the name of the index you want to create, and table_name is the name of the table on which you want to create the index. You can also specify one or more column names in parentheses to indicate which columns you want to include in the index.
For example, let's say you have a table called "employees" with columns "employee_id", "last_name", and "first_name", and you want to create an index on the "last_name" column. You can do this with the following SQL statement,
CREATE INDEX emp_last_name_idx
ON employees (last_name);
This will create an index called "emp_last_name_idx" on the "last_name" column of the "employees" table. You can then use this index to improve the performance of queries that filter or sort by the "last_name" column.