Return number of rows affected by UPDATE statements

How can I get the number of rows affected by an UPDATE query in a Stored Procedure (SQL Server 2005), as a resultset. e.g.

CREATE PROCEDURE UpdateTables
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    UPDATE Table1 Set Column = 0 WHERE Column IS NULL
    UPDATE Table2 Set Column = 0 WHERE Column IS NULL
    UPDATE Table3 Set Column = 0 WHERE Column IS NULL
    UPDATE Table4 Set Column = 0 WHERE Column IS NULL
END

Then return:

Table1    Table2    Table3    Table4
32        45        0         3

CREATE PROCEDURE UpdateTables
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
    DECLARE @RowCount1 INTEGER
    DECLARE @RowCount2 INTEGER
    DECLARE @RowCount3 INTEGER
    DECLARE @RowCount4 INTEGER

    UPDATE Table1 Set Column = 0 WHERE Column IS NULL
    SELECT @RowCount1 = @@ROWCOUNT
    UPDATE Table2 Set Column = 0 WHERE Column IS NULL
    SELECT @RowCount2 = @@ROWCOUNT
    UPDATE Table3 Set Column = 0 WHERE Column IS NULL
    SELECT @RowCount3 = @@ROWCOUNT
    UPDATE Table4 Set Column = 0 WHERE Column IS NULL
    SELECT @RowCount4 = @@ROWCOUNT

    SELECT @RowCount1 AS Table1, @RowCount2 AS Table2, @RowCount3 AS Table3, @RowCount4 AS Table4
END

This is exactly what the OUTPUT clause in SQL Server 2005 onwards is excellent for.

EXAMPLE

CREATE TABLE [dbo].[test_table](
	[LockId] [int] IDENTITY(1,1) NOT NULL,
	[StartTime] [datetime] NULL,
	[EndTime] [datetime] NULL,
PRIMARY KEY CLUSTERED 
(
	[LockId] ASC
) ON [PRIMARY]
) ON [PRIMARY]

INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 07','2009 JUL 07')
INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 08','2009 JUL 08')
INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 09','2009 JUL 09')
INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 10','2009 JUL 10')
INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 11','2009 JUL 11')
INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 12','2009 JUL 12')
INSERT INTO test_table(StartTime, EndTime)
VALUES('2009 JUL 13','2009 JUL 13')

UPDATE test_table
    SET StartTime = '2011 JUL 01'
    OUTPUT INSERTED.* -- INSERTED reflect the value after the UPDATE, INSERT, or MERGE statement is completed 
WHERE
    StartTime > '2009 JUL 09'

Results in the following being returned

    LockId StartTime                EndTime
-------------------------------------------------------
4	   2011-07-01 00:00:00.000	2009-07-10 00:00:00.000
5	   2011-07-01 00:00:00.000	2009-07-11 00:00:00.000
6	   2011-07-01 00:00:00.000	2009-07-12 00:00:00.000
7	   2011-07-01 00:00:00.000	2009-07-13 00:00:00.000

In your particular case, since you cannot use aggregate functions with OUTPUT, you need to capture the output of INSERTED.* in a table variable or temporary table and count the records. For example,

DECLARE @temp TABLE (
  [LockId] [int],
  [StartTime] [datetime] NULL,
  [EndTime] [datetime] NULL 
)

UPDATE test_table
    SET StartTime = '2011 JUL 01'
    OUTPUT INSERTED.* INTO @temp
WHERE
    StartTime > '2009 JUL 09'


-- now get the count of affected records
SELECT COUNT(*) FROM @temp

You might need to collect the stats as you go, but @@ROWCOUNT captures this:

declare @Fish table (
Name varchar(32)
)

insert into @Fish values ('Cod')
insert into @Fish values ('Salmon')
insert into @Fish values ('Butterfish')
update @Fish set Name = 'LurpackFish' where Name = 'Butterfish'
select @@ROWCOUNT  --gives 1

update @Fish set Name = 'Dinner'
select @@ROWCOUNT -- gives 3