Question

我有一张桌子，如上图所示。对于各种系统及其资源类型，我有行。 RAM，HDD，CPU等。另外，对于每种资源类型，我有一个实际上是（RevisionId）＆amp;的列R_ID。每次更新时递增1。

示例：下面我的列数很少

（Machinename-＆GT;资源 - ＆GT; R_Id-＆GT; MemorySizeInGb）

cbedev - ＆gt; HDD-＆gt; 1-＆gt; 2048
cbedev-＆GT; HDD-＆GT; 2→1024
cbedev-＆GT; HDD-＆GT; 3→1024
cbedev-＆GT; HDD-将4-＆GT; 1024
cbedev-＆GT; HDD-＆GT; 5→1024
cbedev-＆GT; HDD-＆GT; 6-＆GT; 1024
dev1 - ＆gt; RAM-＆gt; 1-＆gt; 2048
dev1-＆GT;夯＆GT; 2→1024
dev1-＆GT;夯＆GT; 3→1024
cbed2-＆GT; HDD-＆GT; 1→1024
cbed2-＆GT; HDD-＆GT; 2→1024

我想要的是获得每台机器的最高R_ID记录的MemorySizeInGb。所以从上面来看，我想要的输出将是（请注意，我只需要尺寸，下面只是为了清楚地说明事情）。

cbedev-＆GT; HDD-＆GT; 6-＆GT; 1024
dev1-＆GT;夯＆GT; 3→1024
cbed2-＆GT; HDD-＆GT; 2→1024

我也有一个有效的查询，但我怀疑它不会在大量数据的生产中起作用。这是

    SELECT TOP 1 new_resource_value
    FROM event_history_tbls
    WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
    AND event_history_tbls.resource_description = 'RAM'
    AND event_history_tbls.req_dt <= @todate
    AND r_id = (
                SELECT max(r_id)
                FROM event_history_tbls t1
                WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                AND t1.resource_description = 'RAM'
                AND t1.req_dt <= @todate
                )
    GROUP BY new_resource_value
    ,r_id

请告诉我，如果有比上述更优化的解决方案。提前致谢。更新

这是我的实际查询

SELECT env_name
    ,sys_fqdn_name
    ,ipv4
    ,(
        (
            CASE 
                WHEN (
                        IsNULL((
                                SELECT TOP 1 new_resource_value
                                FROM event_history_tbls
                                WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                    AND event_history_tbls.resource_description = 'RAM'
                                    AND event_history_tbls.req_dt <= @todate
                                    AND r_id = (
                                        SELECT max(r_id)
                                        FROM event_history_tbls t1
                                        WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                            AND t1.resource_description = 'RAM'
                                            AND t1.req_dt <= @todate
                                        )
                                GROUP BY new_resource_value
                                    ,r_id
                                ), 0) = 0
                        )
                    THEN cast(physical_memory AS FLOAT)
                ELSE cast(IsNULL((
                                SELECT TOP 1 new_resource_value
                                FROM event_history_tbls
                                WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                    AND event_history_tbls.resource_description = 'RAM'
                                    AND event_history_tbls.req_dt <= @todate
                                    AND r_id = (
                                        SELECT max(r_id)
                                        FROM event_history_tbls t1
                                        WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                            AND t1.resource_description = 'RAM'
                                            AND t1.req_dt <= @todate
                                        )
                                GROUP BY new_resource_value
                                    ,r_id
                                ), 0) AS FLOAT)
                END
            )
        ) PHYSICAL_MEMORY
    ,no_of_hdd
    ,(
        (
            CASE 
                WHEN (
                        IsNULL((
                                SELECT TOP 1 new_resource_value
                                FROM event_history_tbls
                                WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                    AND event_history_tbls.resource_description = 'HDD'
                                    AND event_history_tbls.req_dt <= @todate
                                    AND r_id = (
                                        SELECT max(r_id)
                                        FROM event_history_tbls t1
                                        WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                            AND t1.resource_description = 'HDD'
                                            AND t1.req_dt <= @todate
                                        )
                                GROUP BY new_resource_value
                                    ,r_id
                                ), 0) = 0
                        )
                    THEN cast(total_size_hdd AS FLOAT)
                ELSE cast(IsNULL((
                                SELECT TOP 1 new_resource_value
                                FROM event_history_tbls
                                WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                    AND event_history_tbls.resource_description = 'HDD'
                                    AND event_history_tbls.req_dt <= @todate
                                    AND r_id = (
                                        SELECT max(r_id)
                                        FROM event_history_tbls t1
                                        WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                            AND t1.resource_description = 'HDD'
                                            AND t1.req_dt <= @todate
                                        )
                                GROUP BY new_resource_value
                                    ,r_id
                                ), 0) AS FLOAT)
                END
            )
        ) TOTAL_SIZE_HDD
    ,(
        CASE 
            WHEN (
                    IsNULL((
                            SELECT TOP 1 new_resource_value
                            FROM event_history_tbls
                            WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                AND event_history_tbls.resource_description = 'CPU'
                                AND event_history_tbls.req_dt <= @todate
                                AND r_id = (
                                    SELECT max(r_id)
                                    FROM event_history_tbls t1
                                    WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                        AND t1.resource_description = 'CPU'
                                        AND t1.req_dt <= @todate
                                    )
                            GROUP BY new_resource_value
                                ,r_id
                            ), 0) = 0
                    )
                THEN no_of_cpu
            ELSE cast(IsNULL((
                            SELECT TOP 1 new_resource_value
                            FROM event_history_tbls
                            WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                AND event_history_tbls.resource_description = 'CPU'
                                AND event_history_tbls.req_dt <= @todate
                                AND r_id = (
                                    SELECT max(r_id)
                                    FROM event_history_tbls t1
                                    WHERE t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name
                                        AND t1.resource_description = 'CPU'
                                        AND t1.req_dt <= @todate
                                    )
                            GROUP BY new_resource_value
                                ,r_id
                            ), 0) AS FLOAT)
            END
        ) NO_OF_CPU
    ,cpu_core_each
    ,environment
FROM sys_hdwr_dtls
WHERE UPPER(sys_hdwr_dtls.env_name) LIKE @envname
    AND UPPER(sys_hdwr_dtls.sys_fqdn_name) LIKE @machinename
    AND Flag = 1

Answer 1

使用Row_Number。

with cte_1
as
(SELECT *,ROW_NUMBER() OVER(PARTITION BY Machinename,Resource ORDER BY  R_ID desc) RNO
FROM Yourtable)
SELECT *
FROM cte_1
WHERE Rno=1

所以你的脚本将如下所示。你需要纠正似乎错误的条件（t1.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name）。

;WITH cte_1
AS
    (SELECT *,ROW_NUMBER()OVER(PARTITION BY Machinename,Resourse ORDER BY r_id desc ) RNO
    FROM event_history_tbls
    WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name -- Place proper condition (@gordon already pointed out this)
    AND event_history_tbls.resource_description = 'RAM'
    AND event_history_tbls.req_dt <= @todate)
SELECT *
FROM cte_1
WHERE RNO=1

Answer 2

如果我认为你的问题是一个相关的子查询，那么最有效的代码可能就是：

SELECT TOP 1 new_resource_value
FROM event_history_tbls
WHERE event_history_tbls.sys_fqdn_name = sys_hdwr_dtls.sys_fqdn_name AND
      event_history_tbls.resource_description = 'RAM' AND
      event_history_tbls.req_dt <= @todate
ORDER BY r_id DESC

GROUP BY和子查询不是必需的。

为了提高性能，您需要event_history_tbls(sys_fqdn_name, resource_description, req_dt)上的索引。

Answer 3

试试这个：

SELECT Machinename,Resource,R_Id,MemorySizeInGb
FROM TableName t1
WHERE R_Id =( SELECT MAX(R_Id) 
              FROM TableName t2 
              WHERE t1.Machinename = t2.Machinename AND t1.Resource=t2.Resource)

获取t-sql

3 个答案: