Question

Problem: Two tables, first one contains userid(constraint fk) and column ‘name’, second table contains two columns of int and id(foreign key), what I need, is to find max(column1-column2) and assign it with name from first table;

what I was doing:
mysql>

select u.name, MAX(table2.column1-table2.column2) As var 
  from table1 u, table2 b 
 where u.userID(from table1) = b.userID(from table2)
   and (b.column1-b.column2) = var;

in this case it says “unknown column var”, is it possible withoud triggers/procedures?

any1?:)

Answer 1

Perhaps try a subquery instead?

select u.name, (b.column1 - b.column2) as var 
  from table1 u, table2 b 
 where u.userID(from table1) = b.userID(from table2)
   and (b.column1-b.column2) = ( select MAX(column1 - column2) from table2);