技術標籤：方法總結sqlsqlserver

庫存賬齡報表開發總結——Sqlserver LAG()的使用

• 開發需求

  根據出入庫流水明細，查詢對應產品庫存狀態：包含庫齡、庫存量及其金額等。

  注意:出庫按照先入先出的規則進行。

  例如:

  物品	數量	日期
  A	10	2020-01-01
  A	20	2020-02-01
  A	30	2020-03-03
  A	-5	2020-04-10
  A	-35	2020-05-15
  A	300	2020-06-18
  A	-60	2020-11-10
  A	90	2020-11-30
  A	-100	2020-12-12
  B	20	2020-07-15
  B	40	2020-10-11
  B	-30	2020-11-11

  上面表示一個出入庫流水明細

  -- 建表，並插入資料
  CREATE TABLE T_StkFlowDetail(
  	id int
   
   primary key not null,
  	goods_code varchar(20) null,
  	num decimal(16,7) null,
  	stk_date date not null
  )
  
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (1, 'A', 10.0000000, '2020-01-01');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (2, 'A',
   
   20.0000000, '2020-02-01');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (3, 'A', 30.0000000, '2020-03-03');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (4, 'A', -5.0000000, '2020-04-10');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]
   
  ) VALUES (5, 'A', -35.0000000, '2020-05-15');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (6, 'A', 300.0000000, '2020-06-18');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (7, 'A', -60.0000000, '2020-11-10');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (8, 'A', 90.0000000, '2020-11-30');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (9, 'A', -100.0000000, '2020-12-12');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (10, 'B', 20.0000000, '2020-07-15');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (11, 'B', 40.0000000, '2020-10-11');
  INSERT INTO [dbo].[T_StkFlowDetail]([id], [goods_code], [num], [stk_date]) VALUES (12, 'B', -30.0000000, '2020-11-11');
  

  以2020-12-31為截止日期去判定最終展示報表形式

  物品	庫存	0-60天	61-120天	121-180天	181-240天	241-300天	301-360天
  A	250	90	0	0	160	0	0
  B	30	0	30	0	0	0	0

• 需求分析

  • 根據每次入庫時間獲取各時間段的庫齡

  • 根據出庫按照先入先出的規則扣減庫存

  • 根據庫齡將對應的庫存、金額等相關資料展示

  • 綜上：該報表的難度在於如何先入先出的扣減庫存

• 函式講解

  • LAG 詳細介紹:https://www.yiibai.com/sqlserver/sql-server-lag-function.html

    SQL Server LAG()是一個Window函式，它提供對當前行之前的指定物理偏移量的行的訪問。

    換句話說，通過使用LAG()函式，可以從當前行訪問上一行的資料或上一行之前的行，依此類推。

    LAG()函式對於將當前行的值與前一行的值進行比較非常有用

    -- 使用語法
    LAG(return_value ,offset [,default]) 
    OVER (
        [PARTITION BY partition_expression, ... ]
        ORDER BY sort_expression [ASC | DESC], ...
    )
    

  • DATEDIFF 詳細介紹:https://www.yiibai.com/sqlserver/sql-server-datediff-function.html

    計算年，月，周等兩個日期之間的差值

    -- 使用語法
    DATEDIFF( date_part , start_date , end_date
    

• 解決方案

  • 查詢每個物品各時間段有庫存情況下的庫齡

  SELECT
  	goods_code,
  	stk_date,
  	diff_days,
  	current_stk_nums,
  	current_stk_nums - ISNULL( LAG ( current_stk_nums ) OVER ( partition BY goods_code ORDER BY stk_date ), 0 ) current_stk_row_nums 
  FROM
  	(
  	SELECT
  		goods_code,
  		num,
  		stk_date,
  		DATEDIFF( DAY, stk_date, '2020-12-31' ) diff_days,
  		SUM ( CASE WHEN num < 0 THEN num ELSE 0 END ) OVER ( PARTITION BY goods_code ) + SUM ( CASE WHEN num > 0 THEN num ELSE 0 END ) OVER ( PARTITION BY goods_code ORDER BY stk_date ) current_stk_nums 
  	FROM
  		T_StkFlowDetail 
  	WHERE
  		stk_date <= '2020-12-31' 
  	) t 
  WHERE
  	current_stk_nums > 0 
  	AND num > 0
  

  • 執行結果
    

  • 此處建議將上述sql寫成函式，方便報表輸出

    CREATE FUNCTION [dbo].[FUNC_GetStockAge] ( @end_date DATE ) RETURNS TABLE AS RETURN (
    	SELECT
    		goods_code,
    		stk_date,
    		diff_days,
    		current_stk_nums,
    		current_stk_nums - ISNULL( LAG ( current_stk_nums ) OVER ( partition BY goods_code ORDER BY stk_date ), 0 ) current_stk_row_nums 
    	FROM
    		(
    		SELECT
    			goods_code,
    			num,
    			stk_date,
    			DATEDIFF( DAY, stk_date, @end_date ) diff_days,
    			SUM ( CASE WHEN num < 0 THEN num ELSE 0 END ) OVER ( PARTITION BY goods_code ) + SUM ( CASE WHEN num > 0 THEN num ELSE 0 END ) OVER ( PARTITION BY goods_code ORDER BY stk_date ) current_stk_nums 
    		FROM
    			T_StkFlowDetail 
    		WHERE
    			stk_date <= @end_date
    		) t 
    	WHERE
    		current_stk_nums > 0 
    	AND num > 0 
    )
    

• 報表輸出語句

  SELECT 
  	t.goods_code '物品', 
  	t.num '庫存',
  	SUM(IIF(t1.diff_days BETWEEN 0 AND 60,t1.current_stk_row_nums,0)) AS '0-60天',
  	SUM(IIF(t1.diff_days BETWEEN 61 AND 120,t1.current_stk_row_nums,0)) AS '61-120天',
  	SUM(IIF(t1.diff_days BETWEEN 121 AND 180,t1.current_stk_row_nums,0)) AS '121-180天',
  	SUM(IIF(t1.diff_days BETWEEN 181 AND 240,t1.current_stk_row_nums,0)) AS '181-240天',
  	SUM(IIF(t1.diff_days BETWEEN 241 AND 300,t1.current_stk_row_nums,0)) AS '241-300天',
  	SUM(IIF(t1.diff_days BETWEEN 301 AND 360,t1.current_stk_row_nums,0)) AS '301-360天'
  FROM (
  	-- 截止2020-12-31各物品的庫存
  	SELECT goods_code,SUM(num) num FROM T_StkFlowDetail
  	WHERE stk_date < '2020-12-31'
  	GROUP BY goods_code
  	HAVING SUM(num) > 0 
  )t
  LEFT JOIN FUNC_GetStockAge('2020-12-31') t1 ON t1.goods_code = t.goods_code
  WHERE t.num > 0
  GROUP BY t.goods_code,t.num
  

• 輸出結果