如何判断一个月中出现星期三的天数总共有几天

declare @dt varchar(7)
set @dt='2011-06'  --如要判断别的月份改这里
select count(*) from master..spt_values 
where type='p' and datepart(dw,dateadd(d,number,@dt+'-01'))=4 and convert(varchar(7),dateadd(d,number,'2011-06-01'),120)=@dt
/*
-----------
5

(1 行受影响)
*/

select sum(case when datename(weekday,date) = N'星期三' then 1 else 0 end)
from tb
where convert(varchar(6),date,112) = '201106'

declare @dt varchar(7)
set @dt='2011-06'
select count(*) from master..spt_values 
where type='p' and datepart(dw,dateadd(d,number,@dt+'-01'))=4 and convert(varchar(7),dateadd(d,number,@dt+'-01'),120)=@dt
/*
-----------
5

(1 行受影响)
*/

select count(*) from master..spt_values 
where type='p' and 
datename(weekday,dateadd(day,number,'2011-06-01'))='星期三' 
and dateadd(day,number,'2011-06-01') between  '2011-06-01' and '2011-06-30'


----------- 
5

（所影响的行数为 1 行）