What is the method for deduplicating data in a Teradata table?

In Teradata, there are several methods available for removing duplicate data from tables.

1. By using the DISTINCT keyword: The DISTINCT keyword in a SELECT statement can eliminate duplicate rows from the result set. For example:
2. Select all unique rows from the table named table_name.
3. This statement will return all non-duplicate rows in the table.
4. By using a QUALIFY clause with the ROW_NUMBER function, it is possible to remove duplicate rows from the table. The ROW_NUMBER function assigns a unique number to each row, allowing the QUALIFY clause to filter out unique rows based on this number. For example:
5. Retrieve all columns from the table where the row number is equal to 1 within each partition ordered by the specified column.
6. This statement will return the rows in the table with duplicates removed based on the column_name column.
7. By using the GROUP BY clause, data can be grouped based on specified columns and aggregate functions can be applied to each group. Including all columns in the GROUP BY clause can eliminate duplicate rows in the table. For example:
8. Choose column 1 through column n from table_name and organize the results based on the specified columns.
9. This statement will return the rows in the table that have been deduplicated based on the specified column.

These methods can be chosen according to specific needs to deduplicate data effectively.