MSSQL：以下代码的替代方法，这需要太多时间才能获得结果

Question

我想知道如何简单地编写下面的代码，同时我也有兴趣避免代码重复。有没有别的办法。要做的是

无论 [invoices_global] table 的字段发生什么变化，这些变化都会以 old_value、[=37 的格式作为新记录插入=]、field_changed 在更改日志中 table。
单个字段可能会被许多用户更新，所以应该是最新的，这就是为什么我在代码中提到 last_updated_datetime desc。
需要避免重复。
性能提升，因为我为单个 ap_work_id 多次调用相同的 table。获取结果需要 18 秒 - 40000 个中有 2000 个。

仅供参考，system_id 和 ap_work_id 相同。

     SELECT
         api.ap_work_id,
         api.invoice_status,
         api.po_number,
         api.po_value,
         api.region,
         api.invoice_value,
         api.invoice_value_currency,
         em3.employee_full_name AS invoice_owner,
         (
             **SELECT TOP 1
                 old_value
             FROM    change_log cl
             WHERE  field_changed = 'ARIBA INVOICE ID' AND api.ap_work_id = cl.
             system_id AND system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS bot_ariba_id_value,
         (
             **SELECT TOP 1
                 new_value
             FROM   change_log cl
             WHERE  field_changed = 'ARIBA INVOICE ID' AND api.ap_work_id = cl.
             system_id AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS processor_ariba_id_value,
         (
             **SELECT TOP 1
                 old_value
             FROM   change_log cl
             WHERE  field_changed = 'PO NUMBER' AND api.ap_work_id = cl.system_id AND
             cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS bot_po_number,
         (
             **SELECT TOP 1
                 new_value
             FROM   change_log cl
             WHERE  field_changed = 'PO NUMBER' AND api.ap_work_id = cl.system_id AND
             cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS processor_po_number,
         (
             **SELECT TOP 1
                 old_value
             FROM   change_log cl
             WHERE  field_changed = 'VENDOR NAME' AND api.ap_work_id = cl.system_id
             AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS bot_vendor_name,
         (
             **SELECT TOP 1
                 new_value
             FROM   change_log cl
             WHERE  field_changed = 'VENDOR NAME' AND api.ap_work_id = cl.system_id
             AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS processor_vendor_name,
         (
             **SELECT TOP 1
                 old_value
             FROM   change_log cl
             WHERE  field_changed = 'INVOICE VALUE' AND api.ap_work_id = cl.system_id
             AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS bot_invoice_value,
         (
             **SELECT TOP 1
                 new_value
             FROM   change_log cl
             WHERE  field_changed = 'INVOICE VALUE' AND api.ap_work_id = cl.system_id
             AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS processor_invoice_value,
         (
             **SELECT TOP 1
                 old_value
             FROM   change_log cl
             WHERE  field_changed = 'INVOICE CURRENCY' AND api.ap_work_id = cl.
             system_id AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS bot_invoice_currency,
         (
             **SELECT TOP 1
                 new_value
             FROM   change_log cl
             WHERE  field_changed = 'INVOICE CURRENCY' AND api.ap_work_id = cl.
             system_id AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS processor_invoice_currency,
         (
             **SELECT TOP 1
                 old_value
             FROM   change_log cl
             WHERE  field_changed = 'INVOICE DATE' AND api.ap_work_id = cl.system_id
             AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS bot_invoice_date,
         (
             **SELECT TOP 1
                 new_value
             FROM   change_log cl
             WHERE  field_changed = 'INVOICE DATE' AND api.ap_work_id = cl.system_id
             AND cl.system_type = 'INVOICE'
             ORDER BY
                     last_updated_datetime DESC**
         ) AS processor_invoice_date
 FROM invoices_global api
     OUTER APPLY
 (
     SELECT TOP 1
         *
     FROM   transactions t
     WHERE  t.po_number = api.po_number AND t.po_number <> ''
     ORDER BY
             t.last_updated_datetime DESC
 ) AS t
     LEFT JOIN employee_master em3
     ON em3.ldap = api.invoice_owner_ldap
     LEFT JOIN vendor v
     ON v.vendor_number = api.vendor_number
     LEFT JOIN cost_center cc
     ON cc.cost_ctr = api.cost_center
 WHERE DATEDIFF(DAY,api.approved_date,GETDATE()) <= 30
 GROUP BY
         api.ap_work_id,
         api.category,
         api.invoice_status,
         api.po_number,
         api.po_value,
         api.region,
         em3.employee_full_name,
         api.invoice_value,
         api.invoice_value_currency,
         api.invoice_date,
         api.due_date,
         api.company_code,
         api.vendor_number,
         api.approved_date,
         t.company_code,
         api.cost_center,
         v.vendor_name,
         v.vendor_number,
         cc.company;

Answer 1

这是一种方法，您

为 system_id 和 field_changed
将派生的 tabled 加入原始 api table 并将值放入各个字段

它目前使用 MAX(CASE())，但您可以将其用作 PIVOT。

此处仅包含 SQL 的顶部（与问题相关）- 您需要在底部进行其他连接。我也没有测试过它（没有 table 结构等）所以我不能保证没有错别字。

; WITH LatestCL AS
        (SELECT * 
            FROM    (SELECT system_id AS ap_work_id, field_changed, old_value, new_value, 
                        ROW_NUMBER () OVER (PARTITION BY system_id, field_changed ORDER BY last_updated_datetime DESC) AS rn
                    FROM change_log
                    WHERE system_type = 'INVOICE'
                    ) cl
            WHERE cl.rn = 1
        )
SELECT  api.ap_work_id,
        api.invoice_status,
        api.po_number,
        api.po_value,
        api.region,
        api.invoice_value,
        api.invoice_value_currency,
        MAX(CASE WHEN field_changed = 'ARIBA INVOICE ID' THEN old_value ELSE NULL END) AS bot_ariba_id_value,
        MAX(CASE WHEN field_changed = 'ARIBA INVOICE ID' THEN new_value ELSE NULL END) AS processor_ariba_id_value,
        MAX(CASE WHEN field_changed = 'PO NUMBER' THEN old_value ELSE NULL END) AS bot_po_number,
        MAX(CASE WHEN field_changed = 'PO NUMBER' THEN new_value ELSE NULL END) AS processor_po_number,
        MAX(CASE WHEN field_changed = 'VENDOR NAME' THEN old_value ELSE NULL END) AS bot_vendor_name,
        MAX(CASE WHEN field_changed = 'VENDOR NAME' THEN new_value ELSE NULL END) AS processor_vendor_name,
        MAX(CASE WHEN field_changed = 'INVOICE VALUE' THEN old_value ELSE NULL END) AS bot_invoice_value,
        MAX(CASE WHEN field_changed = 'INVOICE VALUE' THEN new_value ELSE NULL END) AS processor_invoice_value,
        MAX(CASE WHEN field_changed = 'INVOICE CURRENCY' THEN old_value ELSE NULL END) AS bot_invoice_currency,
        MAX(CASE WHEN field_changed = 'INVOICE CURRENCY' THEN new_value ELSE NULL END) AS processor_invoice_currency,
        MAX(CASE WHEN field_changed = 'INVOICE DATE' THEN old_value ELSE NULL END) AS bot_invoice_date,
        MAX(CASE WHEN field_changed = 'INVOICE DATE' THEN new_value ELSE NULL END) AS processor_invoice_date
FROM    invoices_global api
        INNER JOIN LatestCL ON api.ap_work_id = LatestCL.ap_work_id

MSSQL：以下代码的替代方法，这需要太多时间才能获得结果

MSSQL: Alternative Approach to the below code, this is taking too much time to get results

sql

sql-server

sql-server-2008

mssql-jdbc