Question

我在产品表

中有列，如下所示

name varchar(100)

xdate datetime

如果我从产品表

中选择以下查询

select name
     , DateName( month , DateAdd( month , month(xdate) , 0 ) - 1 ) as xdate  
from Products

选择查询结果，如下所示

名称（列） - xdate（列）

Computer    May

Phone   May

Mouse  May

Grass  April

Usb  April

Glass  February

问题：

如何显示结果如下

名称（列） - xdate（列）

    Computer    May

    Phone   

    Mouse  

    Grass  April

    Usb  

    Glass  February

我只想在选择查询中显示 xdate 以实现此目的。

任何帮助将不胜感激。

由于

Answer 1

尝试此查询

select 
    name, 
    case when num = 1 then xdate else '' end as xdate
from
(
    select 
        name, 
        DateName( month , DateAdd( month , month(xdate) , 0 ) - 1 ) as xdate  ,
        row_number() over (partition by YEAR(XDATE), MONTH(XDATE) order by xdate) as num,
        xdate as real_date
    from Products
) T
order by real_date

Answer 2

您的数据是如何订购的？假设您有一个排序列（在下面的示例中为id），您可以在SQL Server 2012及更高版本上使用LAG函数：

DECLARE @Products TABLE
(id int, name varchar(100), xdate varchar(100))

INSERT INTO @Products (id, name, xdate)
VALUES
(1, 'Computer', 'May'),
(2, 'Phone', 'May'),
(3, 'Mouse', 'May'),
(4, 'Grass', 'April'),
(5, 'Usb', 'April'),
(6, 'Glass', 'February')

SELECT p.name,
    CASE LAG(p.xdate, 1,0) OVER (ORDER BY p.id)
        WHEN p.xdate THEN ''
        ELSE p.xdate
    END AS xdate
FROM @Products p

结果：

name        xdate
Computer    May
Phone   
Mouse   
Grass       April
Usb 
Glass       February

Answer 3

对于SQL 2012+，我认为George拥有最佳解决方案。

SQL 2005解决方案

SELECT  P.id,
        name,
        ISNULL(CA.xdate,'') AS xDate
FROM Products p
OUTER APPLY(
                SELECT DateName( month , DateAdd( month , month(xdate) , 0 ) - 1 )
                FROM Products
                GROUP BY xdate
                HAVING MIN(ID) = p.id
           ) CA(xdate)
ORDER BY ID

SQL 2008解决方案

SELECT  id,
        name,
        CASE WHEN ROW_NUMBER() OVER (PARTITION BY CA.xDate ORDER BY ID) = 1
                THEN CA.xdate
            ELSE ''
        END AS xdate
FROM Products
CROSS APPLY(SELECT DateName( month , DateAdd( month , month(xdate) , 0 ) - 1 )) CA(xdate)
ORDER BY ID

Answer 4

低技术（不太优雅）的解决方案（适用于SQL Server 2000）：

select t.name, case when t.name = minSQ.minName then minSQ.mnth else '' end 
from Products t 
    join (select MIN(name) minName, DATENAME(month,xdate) mnth from Products group by DATENAME(month,xdate)) minSQ on DateName(month, t.xdate) = minSQ.mnth
order by t.xdate

T sql group仅按列值

4 个答案:

SQL 2005解决方案

SQL 2008解决方案