isnull(字段,0)-------- Transact-SQL 参考
ISNULL
使用指定的替换值替换 NULL。语法
ISNULL ( check_expression , replacement_value ) 参数
check_expression将被检查是否为 NULL的表达式。check_expression 可以是任何类型的。replacement_value在 check_expression 为 NULL时将返回的表达式。replacement_value 必须与 check_expresssion 具有相同的类型。 返回类型
返回与 check_expression 相同的类型。注释
如果 check_expression 不为 NULL,那么返回该表达式的值;否则返回 replacement_value。示例
A. 将 ISNULL 与 AVG 一起使用
下面的示例查找所有书的平均价格,用值 $10.00 替换 titles 表的 price 列中的所有 NULL 条目。USE pubs
GO
SELECT AVG(ISNULL(price, $10.00))
FROM titles
GO下面是结果集:--------------------------
14.24 (1 row(s) affected)B. 使用 ISNULL
下面的示例为 titles 表中的所有书选择书名、类型及价格。如果一个书名的价格是 NULL,那么在结果集中显示的价格为 0.00。USE pubs
GO
SELECT SUBSTRING(title, 1, 15) AS Title, type AS Type,
ISNULL(price, 0.00) AS Price
FROM titles
GO下面是结果集:Title Type Price
--------------- ------------ --------------------------
The Busy Execut business 19.99
Cooking with Co business 11.95
You Can Combat business 2.99
Straight Talk A business 19.99
Silicon Valley mod_cook 19.99
The Gourmet Mic mod_cook 2.99
The Psychology UNDECIDED 0.00
But Is It User popular_comp 22.95
Secrets of Sili popular_comp 20.00
Net Etiquette popular_comp 0.00
Computer Phobic psychology 21.59
Is Anger the En psychology 10.95
Life Without Fe psychology 7.00
Prolonged Data psychology 19.99
Emotional Secur psychology 7.99
Onions, Leeks, trad_cook 20.95
Fifty Years in trad_cook 11.95
Sushi, Anyone? trad_cook 14.99 (18 row(s) affected)
请参见表达式IS [NOT] NULL系统函数WHERE©1988-2000 Microsoft Corporation。保留所有权利。
ISNULL
使用指定的替换值替换 NULL。语法
ISNULL ( check_expression , replacement_value ) 参数
check_expression将被检查是否为 NULL的表达式。check_expression 可以是任何类型的。replacement_value在 check_expression 为 NULL时将返回的表达式。replacement_value 必须与 check_expresssion 具有相同的类型。 返回类型
返回与 check_expression 相同的类型。注释
如果 check_expression 不为 NULL,那么返回该表达式的值;否则返回 replacement_value。示例
A. 将 ISNULL 与 AVG 一起使用
下面的示例查找所有书的平均价格,用值 $10.00 替换 titles 表的 price 列中的所有 NULL 条目。USE pubs
GO
SELECT AVG(ISNULL(price, $10.00))
FROM titles
GO下面是结果集:--------------------------
14.24 (1 row(s) affected)B. 使用 ISNULL
下面的示例为 titles 表中的所有书选择书名、类型及价格。如果一个书名的价格是 NULL,那么在结果集中显示的价格为 0.00。USE pubs
GO
SELECT SUBSTRING(title, 1, 15) AS Title, type AS Type,
ISNULL(price, 0.00) AS Price
FROM titles
GO下面是结果集:Title Type Price
--------------- ------------ --------------------------
The Busy Execut business 19.99
Cooking with Co business 11.95
You Can Combat business 2.99
Straight Talk A business 19.99
Silicon Valley mod_cook 19.99
The Gourmet Mic mod_cook 2.99
The Psychology UNDECIDED 0.00
But Is It User popular_comp 22.95
Secrets of Sili popular_comp 20.00
Net Etiquette popular_comp 0.00
Computer Phobic psychology 21.59
Is Anger the En psychology 10.95
Life Without Fe psychology 7.00
Prolonged Data psychology 19.99
Emotional Secur psychology 7.99
Onions, Leeks, trad_cook 20.95
Fifty Years in trad_cook 11.95
Sushi, Anyone? trad_cook 14.99 (18 row(s) affected)
请参见表达式IS [NOT] NULL系统函数WHERE©1988-2000 Microsoft Corporation。保留所有权利。
@type1 smallint,@type2 smallint,@id char(18),@number int output,@price numeric(19,2) = 0 output
AS
或:
if @price is null set @price=0
或
if @price is null then set @price=0
@type1 smallint,@type2 smallint,@id char(18),@number int output,@price numeric(19,2) output
AS
if @type1=1/*买方*/
begin
if @type2=1 /*成功交易*/
begin
select @number=count(form_id)
from orderlist
where orderlist.user_id=@id and orderlist.re='交易成功'
select @price=sum(p_bm*number)
from shoplist
where shoplist.form_id in(
select orderlist.form_id
from orderlist
where orderlist.user_id=@id and orderlist.re='交易成功')
end
else/*未成功交易*/
begin
select @number=count(form_id)
from orderlist
where orderlist.user_id=@id and orderlist.re='正在交易中'
select @price=sum(p_bm*number)
from shoplist
where shoplist.form_id in(
select orderlist.form_id
from orderlist
where orderlist.user_id=@id and orderlist.re='正在交易中')
end
end
else if @type1=2/*卖方*/
begin
if @type2=1 /*成功交易*/
begin
select @number=count(form_id)
from orderlist
where orderlist.p_gys_id=@id and orderlist.re='交易成功'
select @price=sum(p_newprice*number)
from shoplist
where shoplist.form_id in(
select orderlist.form_id
from orderlist
where orderlist.p_gys_id=@id and orderlist.re='交易成功')
end
else/*未成功交易*/
begin
select @number=count(form_id)
from orderlist
where orderlist.p_gys_id=@id and orderlist.re='正在交易中'
select @price=sum(p_newprice*number)
from shoplist
where shoplist.form_id in(
select orderlist.form_id
from orderlist
where orderlist.p_gys_id=@id and orderlist.re='正在交易中')
end
select @number=isnull(@number,0),@price=isnull(@price,0)
end
如此种方法应该可以解决select case when @price is null then 0 else @price end
如果不行的话,变通一下就可以了