我有一个T-SQL
查询,其性能非常差,直到它时程。罪魁祸首是带有嵌入式查询的两个嵌套案例语句:
SELECT
CASE
WHEN b.month_type = (CASE
WHEN dbo.CURRENT_BUSINESSDAY(GETDATE()) >= 8 THEN 'Current Month BD2'
ELSE (CASE
WHEN dbo.CURRENT_BUSINESSDAY(GETDATE()) < 8 AND
(SELECT
MAX(b.cal_start_date)
FROM factbillingcollectionhistory a
JOIN dimdateperiod b
ON a.fiscal_month = b.fsc_period)
<> (SELECT
MAX(cal_start_date)
FROM dimdateperiod) THEN 'Current Reporting Month'
ELSE 'Current Month BD2'
END)
END) THEN a.BILLINGS_BUDGET
ELSE 0
END
AS BILLINGS_BUDGET,
CASE
WHEN b.month_type = (CASE
WHEN dbo.CURRENT_BUSINESSDAY(GETDATE()) >= 8 THEN 'Current Month BD2'
ELSE (CASE
WHEN dbo.CURRENT_BUSINESSDAY(GETDATE()) < 8 AND
(SELECT
MAX(b.cal_start_date)
FROM factbillingcollectionhistory a
JOIN dimdateperiod b
ON a.fiscal_month = b.fsc_period)
<> (SELECT
MAX(cal_start_date)
FROM dimdateperiod) THEN 'Current Reporting Month'
ELSE 'Current Month BD2'
END)
END) THEN a.COLLECTION_GOALS
ELSE 0
END
AS COLLECTION_GOALS
CURRENT_BUSINESSDAY
函数确实可以执行它所描述的。
CASE
的逻辑是根据我们在报告周期中的位置以及是否收到更新的目标文件返回目标值。如果尚未BD8,请检查我们是否已收到新文件(通过比较最大日期)。如果我们已收到它,请将该值返回报告,否则返回上个月的值。如果是在BD8之后,并且我们仍然没有新文件,它应该返回" 0",这将使我们的流程失败,并让我们知道他们没有按时提供数据。
是否有更有效的方法来脚本这种逻辑,可以防止查询时间计时?请记住,此脚本被用来在表格模型中构建表,因此只有选择才在播放中...没有可变声明或任何类似的内容。
想法?
由于casten_goals和billings_budget中的情况相同,所以我建议将逻辑从内联子征服中移出并从子句中转移到主子句中,例如:
SELECT CASE WHEN b.month_type = z.month_type
THEN a.BILLINGS_BUDGET
ELSE 0
END AS BILLINGS_BUDGET,
CASE WHEN b.month_type = z.month_type
THEN a.COLLECTION_GOALS
ELSE 0
END AS COLLECTION_GOALS
FROM (SELECT CASE WHEN dbo.CURRENT_BUSINESSDAY(GETDATE()) >= 8
THEN 'Current Month BD2'
ELSE (CASE WHEN dbo.CURRENT_BUSINESSDAY(GETDATE()) < 8 AND
(SELECT max(b.cal_start_date)
FROM factbillingcollectionhistory a
JOIN dimdateperiod b
ON a.fiscal_month = b.fsc_period) <> (SELECT max(cal_start_date) FROM dimdateperiod)
THEN 'Current Reporting Month'
ELSE 'Current Month BD2'
END)
END month_type) z
CROSS JOIN
/*... Rest of query */
这应该导致每个查询一次评估一次,而不是查询返回的每一行两次。