Если вы можете выполнить рефакторинг к тому же предложению where, это должно быть возможно.
Я не учел вашу ХАЙВИНГ (Количество ())
SELECT [Date], COUNT(*) AS Total, SUM(CASE WHEN ErrorCode = -2 THEN 1 ELSE 0 END) AS Failures
FROM [Table]
WHERE [Type] = 7 AND [Date] >= '2010-01-01'
GROUP BY [Date]
ORDER BY [Date]
Редактировать: вот некоторые тестовые данные
create table [Table]
(
[ErrorCode] int,
[Type] int,
[Date] datetime
)
insert into [table]([Date], [Type], [ErrorCode] )values ('1 Jan 2010', 7, 0)
insert into [table]([Date], [Type], [ErrorCode] )values ('1 Jan 2010', 7, -2)
insert into [table]([Date], [Type], [ErrorCode] )values ('2 Jan 2010', 7, -2)
insert into [table]([Date], [Type], [ErrorCode] )values ('2 Jan 2010', 8, -2)
insert into [table]([Date], [Type], [ErrorCode] )values ('2 Jan 2010', 7, 1)