Can we delete duplicate records from a table in teradata without using intermediate table

Question

Can we delete duplicate records from a multiset table in teradata without using intermediate table.

Suppose we have 2 rows with values 1, 2, 3 and 1, 2, 3 in my mu

Answer 1

You can't unless the ROWID usage has been enabled on your system (and probablity is quite low). You can easily test it by trying to explain a SELECT ROWID FROM table;

Otherwise there are two possible ways.

Low number of duplicates:

• create a new table as result of SELECT all columns FROM table GROUP BY all columns HAVING COUNT(*) > 1;
• DELETE FROM tab WHERE EXISTS (SELECT * FROM newtab WHERE...)
• INSERT INTO tab SELECT * FROM newtab

High number of duplicates:

• copy to a new table using SELECT DISTINCT * or copy to a SET TABLE to get rid of the duplicates and then re-INSERT back