Hi, i am fresh in sql and teradate. When i used ‘where’ to filter the data from AUG, 2004
WHERE a.num_month<>8 and a.num_year<>2004
The result seems all the data from AUG in different years and from 2004 including all the months are excluded.
Why this happened? Thanks.
Well, this is exactly what you wrote: No data from the year 2004 and no data from any august :-)
You want either a.num_month<>8 OR a.num_year<>2004 or NOT(a.num_month = 8 AND a.num_year = 2004), the latter is a bit easier to understand, see https://en.wikipedia.org/wiki/De_Morgan%27s_laws
a.num_month<>8 OR a.num_year<>2004
NOT(a.num_month = 8 AND a.num_year = 2004)
If you run Explain (F6) you will see that both result in the same search conditions.