没有子查询，两个 "where" 语句和一个 table 语句不起作用

Question

我有一个包含 3 列的 table：name、lastname 和 date。

例如：

Name Lastname Date
Ab   Ab       2008-07-01
Ab   Ab       2006-06-23
Kb   Kb       2008-07-01
Kb   Kb       2007-06-03

我需要找到分配给 2008-07 而不是 2006-06 的人的姓名。所以对于这个例子，输出将是：

Name Lastname Date
Kb   Kb       2008-07-01
Kb   Kb       2007-06-03

我的代码：

select  Name, Lastname, YEAR(date), MONTH(date) from MyTable
where (YEAR(date) = 2008 AND MONTH(date) = 7) AND (YEAR(date) <> 2006 AND MONTH(date) <> 6)

效果不佳，因为实际上什么都没有发生（例如 "blocking" 所有名称的月份都为 6）。我尝试用 UNION 语句来做，但没有什么效果。

请注意，我需要在不使用子查询的情况下执行此操作。

Answer 1

我认为您需要一个 group by 和一个 having 子句，因为您要查找多行：

select  Name, Lastname
from MyTable
group by Name, LastName
having 
    sum(case when YEAR(date) = 2008 AND MONTH(date) = 7 then 1 else 0 end) > 0 and
    sum(case when YEAR(date) = 2006 AND MONTH(date) = 6 then 1 else 0 end) = 0;

having 子句中的每个条件都会计算匹配的行数。 > 0 表示至少有一个。 = 0 表示有 none。这很容易推广到更多条件。

Answer 2

SELECT
    t.*
FROM (
    SELECT
        Name,
        LastName
    FROM #Temp
    GROUP BY Name, LastName
    HAVING
        SUM(CASE WHEN YEAR([Date]) = 2008 AND MONTH([Date]) = 7 THEN 1 ELSE 0 END) = 1
        AND SUM(CASE WHEN YEAR([Date]) = 2006 AND MONTH([Date]) = 6 THEN 1 ELSE 0 END) = 0
)x
INNER JOIN #Temp t
    ON t.Name = x.Name
    AND t.LastName = x.LastName

结果

Name                 LastName             Date
-------------------- -------------------- ----------
Kb                   Kb                   2008-07-01
Kb                   Kb                   2007-06-03

Answer 3

您可以使用一系列外部联接来实现，而无需子查询。

SELECT c1.*
FROM Customers c1
LEFT OUTER JOIN Customers c2 ON
    c1.Name = c2.Name AND c1.LastName = c2.LastName
    AND YEAR(c2.date) = 2006 AND MONTH(c2.date) = 6
LEFT OUTER JOIN Customers c3 ON
    c1.Name = c3.Name AND c1.LastName = c3.LastName
    AND YEAR(c3.date) = 2008 AND MONTH(c3.date) = 7
WHERE 
    c2.date IS NULL
    AND c3.date IS NOT NULL

您断言第一次加入失败，但第二次加入成功。

结果是

Kb Kb 7/1/2008 12:00:00 AM 
Kb Kb 6/3/2007 12:00:00 AM

没有子查询，两个 "where" 语句和一个 table 语句不起作用

Two "where" statements with one table doesn't work without subqueries

sql

tsql

sql-server

where

sql-server-2008