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sum grouping with NULL/ Not null
Clark Pokejn
Дата: 27.11.2009 16:10:58
Simple -
select sum(x) from (select null x from dual union all (select 1 x from dual)). The result is
1
But
sum(null+1) is Null
.
non ANSI?
tru55
Дата: 27.11.2009 16:13:41
SQL Reference
Aggregate Functions
All aggregate functions except COUNT(*) and GROUPING ignore nulls.
suPPLer
Дата: 27.11.2009 16:18:58
Clark Pokejn
Simple -
select sum(x) from (select null x from dual union all (select 1 x from dual)). The result is
1
But
sum(null+1) is Null
.
non ANSI?
Подсказка: NULL + 1 = NULL.
_Alex_SMIRNOV_
Дата: 27.11.2009 16:22:44
- Групповая функция SUM пропускает NULL значения.
- NULL + 1 <> select sum(x) from (select null x from dual union all select 1 x from dual)