UC知道帮我解释一下下面的存储过程，看不太明白，特别是union的作用
来源：百度知道 编辑：UC知道 时间：2024/05/25 19:04:26
CREATE PROCEDURE 本月概况
@Date1 datetime
AS
SELECT '接收月小计' AS 项目,Count(*) AS 数量,10 AS S
FROM tabstate
WHERE year(writeindate)=year(@date1) and month(writeindate)=month(@date1) and writeflag=1
union
select '接收年累计' as 项目,count(*) as 数量,20 as s
from tabstate
where year(writeindate)=year(@date1) and writeflag=1
ORDER BY S
GO
@Date1 datetime
AS
SELECT '接收月小计' AS 项目,Count(*) AS 数量,10 AS S
FROM tabstate
WHERE year(writeindate)=year(@date1) and month(writeindate)=month(@date1) and writeflag=1
union
select '接收年累计' as 项目,count(*) as 数量,20 as s
from tabstate
where year(writeindate)=year(@date1) and writeflag=1
ORDER BY S
GO
说明白了，存储过程也是就是段SQL语句，只是为了方便再用的时候再写再编译，
CREATE PROCEDURE 本月概况 // 这里是定义
@Date1 datetime //定义一个变量
AS
SELECT '接收月小计' AS 项目,Count(*) AS 数量,10 AS S
FROM tabstate
WHERE year(writeindate)=year(@date1) and month(writeindate)=month(@date1) and writeflag=1 //这是一个select 语句
union //这是一个关键字，用来合并表的。具体语法去看看SQL帮助。
select '接收年累计' as 项目,count(*) as 数量,20 as s
from tabstate
where year(writeindate)=year(@date1) and writeflag=1
ORDER BY S //这也是一个SELECT 语句。
-------------
具体建议你，有不清楚的语法去看看SQL帮助，那里写得很清楚还有例子。
union的作用是把两次查询的结果合并，这个存储过程的作用是查找一个指定日期所在的月和年的统计数据。