SELECT @Count = COUNT(*)
FROM Widgets
WHERE WidgetName = 'foo'

IF ( @Count = 1 ) BEGIN
    SELECT @WidgetId = WidgetId
    FROM Widgets
    WHERE WidgetName = 'foo'
END

SELECT @WidgetId = WidgetId
    FROM Widgets
    WHERE WidgetName = 'foo'

IF @@ROWCOUNT = 1
BEGIN
    --Here you are certain that there's only one matching row found
END
ELSE
BEGIN
    --Here zero or more than one records were found
END

SELECT @WidgetId = MAX(WidgetId)
FROM Widgets
WHERE WidgetName = 'Widget Name'
GROUP BY WidgetName
HAVING COUNT(*) = 1

DECLARE @temp TABLE (
    WidgetId int
)

INSERT INTO @temp
SELECT TOP 2 WidgetId
FROM Widgets
WHERE WidgetName = 'foo'

SELECT @Count = COUNT(*) FROM @temp

IF ( @Count = 1 ) BEGIN
    SELECT @WidgetId = WidgetId FROM @temp
END

declare @WidgetId int
select
    @WidgetId = WidgetId
from Widgets w
where WidgetName='foo'
    and not exists (
        select 1 from Widgets where WidgetName=w.WidgetName and WidgetId<>w.WidgetId
    )