In Oracle, the DISTINCT keyword is used to return only unique values in a result set. This can be useful for removing duplicate rows from a table or for ensuring that a particular value only appears once in a list. However, using DISTINCT can also impact the performance of a query, as it requires the database to perform additional processing to identify and remove duplicate rows.
There are a few different ways to avoid using DISTINCT in Oracle. One option is to use the UNIQUE keyword instead. UNIQUE creates a unique index on the specified column, which can improve performance when querying for unique values. Another option is to use the GROUP BY clause to group the results by a specific column or set of columns. This will return only one row for each group, even if there are duplicate values within the group.