DML

select distinct

a as " "

from A

where

group by

having

order by a desc ,b asc ;

 

 

group by

count()

count(*)

max()

min()

 

with rollup;

(group by +) having count(*)>=7 ;

 

avg(sum())

floor()

 

inner join A  A'  into B B' on  B' PK =A' FK; 

outer join